podvm: Fix variable substitution in rhel podvm builder.

This change will help fix checksum failure issue & perform checksum work with Docker and Podman.

Signed-off-by: Saripalli Lavanya <Saripalli.Lavanya@ibm.com>

src/cloud-api-adaptor/podvm/Dockerfile.podvm_builder.rhel

@@ -16,6 +16,7 @@ ARG RUST_VERSION
 ARG ORG_ID
 ARG ACTIVATION_KEY
 ARG YQ_VERSION
+ARG YQ_CHECKSUM
 
 ENV SMDEV_CONTAINER_OFF=1
 ENV ARCH ${ARCH}
@@ -31,8 +32,8 @@ RUN subscription-manager repos --enable codeready-builder-for-rhel-9-${ARCH}-rpm
     dnf install -y yum-utils gnupg git --allowerasing curl pkg-config clang perl libseccomp-devel gpgme-devel \
     device-mapper-devel qemu-kvm unzip wget libassuan-devel genisoimage cloud-utils-growpart cloud-init; 
 
-ADD https://github.com/mikefarah/yq/releases/download/${YQ_VERSION}/yq_linux_${ARCH/x86_64/amd64} /usr/local/bin/yq
-RUN echo "${YQ_CHECKSUM#sha256:} /usr/local/bin/yq" | sha256sum -c
+RUN curl -L -o /usr/local/bin/yq https://github.com/mikefarah/yq/releases/download/${YQ_VERSION}/yq_linux_${ARCH/x86_64/amd64} \
+    && echo "${YQ_CHECKSUM#sha256:}  /usr/local/bin/yq" | sha256sum -c -
 RUN chmod a+x /usr/local/bin/yq && \
     curl https://dl.google.com/go/go${GO_VERSION}.linux-${ARCH/x86_64/amd64}.tar.gz -o go${GO_VERSION}.linux-${ARCH/x86_64/amd64}.tar.gz && \
     rm -rf /usr/local/go && tar -C /usr/local -xzf go${GO_VERSION}.linux-${ARCH/x86_64/amd64}.tar.gz && \