[sonic-swss]: Update submodule

This submodule update brings in the following changes:

```
50d5be2 Make changes to support compiling on Bullseye with GCC 10 (sonic-net#2216)
0870cf5 [mirrororch]: Implement HW resources availability validation for SPAN/ERSPAN (sonic-net#2187)
f4ec565 [vlanmgrd] fix use-after-free memory issue (sonic-net#2211)
c2de7fc [QosOrch] The notifications cannot be drained in QosOrch in case the first one needs to retry (sonic-net#2206)
5575935 [neighsyncd] increase neighsyncd timeout (sonic-net#2209)
0f06910 [PBH] Implement Edit Flows (sonic-net#2169)
6241bbf Remove redundant and problematic code to skip "pool" field in buffer profile handling (sonic-net#2197)
a55343c [azp]: Set diff coverage threshhold to 80% (sonic-net#2188)
390cae1 [portsorch]: Prevent LAG member configuration when port has active ACL binding (sonic-net#2165)
c1d47e6 [VNET]Fixing nexthop group delete during route change (sonic-net#2198)
8941cc0 [BFD]Registering BFD state change callback during session creation (sonic-net#2202)
680c539 [vxlan] Remove tunnel map objects on VNET tunnel removal (sonic-net#2150)
20dde0c Fix for handling broadcom DNX ASIC to have ipv4 and ipv6 ACL rules in separate tables. (sonic-net#2178)
5b7c949 [FdbOrch] SAI_FDB_EVENT_MOVE generates update with empty update.entry.port_name (sonic-net#2200)
7350d49 [Vxlanmgr] vnet netdev cleanup during config reload fix (sonic-net#2191)
2bef62b Validate LAG has members before mirror session create (sonic-net#2130)
1e4d4ce [VS test] Increase VS test time, skip dpb flaky test (sonic-net#2195)
6eda965 [vstest]Migrating vs tests from using click commands to direct DB access (sonic-net#2179)
```

Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>

dockers/docker-swss-layer-bullseye/Dockerfile.j2

@@ -0,0 +1,22 @@
+{% from "dockers/dockerfile-macros.j2" import install_debian_packages, install_python_wheels, copy_files %}
+FROM docker-config-engine-bullseye
+
+## Make apt-get non-interactive
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update
+
+{% if docker_swss_layer_bullseye_debs.strip() -%}
+# Copy locally-built Debian package dependencies
+{{ copy_files("debs/", docker_swss_layer_bullseye_debs.split(' '), "/debs/") }}
+
+# Install locally-built Debian packages and implicitly install their dependencies
+{{ install_debian_packages(docker_swss_layer_bullseye_debs.split(' ')) }}
+{%- endif %}
+
+RUN apt-get clean -y      && \
+    apt-get autoclean -y  && \
+    apt-get autoremove -y && \
+    rm -rf /debs
+
+ENTRYPOINT ["/usr/local/bin/supervisord"]

rules/docker-swss-layer-bullseye.dep

@@ -0,0 +1,10 @@
+
+DPATH       := $($(DOCKER_SWSS_LAYER_BULLSEYE)_PATH)
+DEP_FILES   := $(SONIC_COMMON_FILES_LIST) rules/docker-swss-layer-bullseye.mk rules/docker-swss-layer-bullseye.dep
+DEP_FILES   += $(SONIC_COMMON_BASE_FILES_LIST)
+DEP_FILES   += $(shell git ls-files $(DPATH))
+
+$(DOCKER_SWSS_LAYER_BULLSEYE)_CACHE_MODE  := GIT_CONTENT_SHA
+$(DOCKER_SWSS_LAYER_BULLSEYE)_DEP_FLAGS   := $(SONIC_COMMON_FLAGS_LIST)
+$(DOCKER_SWSS_LAYER_BULLSEYE)_DEP_FILES   := $(DEP_FILES)
+

rules/docker-swss-layer-bullseye.mk

@@ -0,0 +1,13 @@
+# docker image for sonic swss layer
+
+DOCKER_SWSS_LAYER_BULLSEYE = docker-swss-layer-bullseye.gz
+$(DOCKER_SWSS_LAYER_BULLSEYE)_PATH = $(DOCKERS_PATH)/docker-swss-layer-bullseye
+
+$(DOCKER_SWSS_LAYER_BULLSEYE)_DEPENDS += $(SWSS)
+$(DOCKER_SWSS_LAYER_BULLSEYE)_LOAD_DOCKERS += $(DOCKER_CONFIG_ENGINE_BULLSEYE)
+
+$(DOCKER_SWSS_LAYER_BULLSEYE)_DBG_DEPENDS = $($(DOCKER_CONFIG_ENGINE_BULLSEYE)_DBG_DEPENDS) \
+                                             $(SWSS)
+$(DOCKER_SWSS_LAYER_BULLSEYE)_DBG_IMAGE_PACKAGES = $($(DOCKER_CONFIG_ENGINE_BULLSEYE)_DBG_IMAGE_PACKAGES)
+
+SONIC_DOCKER_IMAGES += $(DOCKER_SWSS_LAYER_BULLSEYE)