[cmake] use OPENTHREAD_PLATFORM_CORE_CONFIG_FILE (#618)

This commit changes the `CMakeList.txt` to use the newly added
`OPENTHREAD_PLATFORM_CORE_CONFIG_FILE` to specify the OT core
config header to use by platform instead of using the project
specific `PROJECT_CORE_CONFIG_FILE` header. It also removed the
use of now deprecated `OPENTHREAD_CONFIG_FILE`.

This allows a project using nrf platform to define its own set
configs, while still using the platform specified one from
`PLATFORM_CORE_CONFIG_FILE` as default for any unspecified
configs.

This commit also adds `#ifndef` check before defining a config in
the `openthread-core-nrf5282xxx-config.h` headers.

CMakeLists.txt

@@ -48,8 +48,7 @@ set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/bin)
 add_subdirectory(openthread)
 
 target_compile_definitions(ot-config INTERFACE
-    OPENTHREAD_CONFIG_FILE="openthread-core-${NRF_PLATFORM}-config.h"
-    OPENTHREAD_PROJECT_CORE_CONFIG_FILE="openthread-core-${NRF_PLATFORM}-config.h"
+    OPENTHREAD_PLATFORM_CORE_CONFIG_FILE="openthread-core-${NRF_PLATFORM}-config.h"
     OPENTHREAD_CORE_CONFIG_PLATFORM_CHECK_FILE="openthread-core-${NRF_PLATFORM}-config-check.h"
 )
 

src/nrf52811/openthread-core-nrf52811-config.h

@@ -213,8 +213,10 @@
  *
  */
 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
+#ifndef OPENTHREAD_CONFIG_MAC_HEADER_IE_SUPPORT
 #define OPENTHREAD_CONFIG_MAC_HEADER_IE_SUPPORT 1
 #endif
+#endif
 
 /**
  * @def RADIO_CONFIG_SRC_MATCH_SHORT_ENTRY_NUM

src/nrf52833/openthread-core-nrf52833-config.h

@@ -265,8 +265,10 @@
  *
  */
 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
+#ifndef OPENTHREAD_CONFIG_MAC_HEADER_IE_SUPPORT
 #define OPENTHREAD_CONFIG_MAC_HEADER_IE_SUPPORT 1
 #endif
+#endif
 
 /**
  * @def RADIO_CONFIG_SRC_MATCH_SHORT_ENTRY_NUM

src/nrf52840/openthread-core-nrf52840-config.h

@@ -265,8 +265,10 @@
  *
  */
 #if OPENTHREAD_CONFIG_TIME_SYNC_ENABLE
+#ifndef OPENTHREAD_CONFIG_MAC_HEADER_IE_SUPPORT
 #define OPENTHREAD_CONFIG_MAC_HEADER_IE_SUPPORT 1
 #endif
+#endif
 
 /**
  * @def RADIO_CONFIG_SRC_MATCH_SHORT_ENTRY_NUM