Enable SDK build with BUILD_SDK variable

ci/yocto-ktn-common.yml

@@ -40,6 +40,7 @@ stages:
   - echo "ACCEPT_FSL_EULA = \"1\"" >> conf/local.conf
   - test -e conf/EULA.conf && echo "include EULA.conf" >> conf/local.conf
   - bitbake $BUILD_TARGETS
+  - bitbake $BUILD_SDKS -c populate_sdk
 
 .release-get-tag-version: &release-get-tag-version
   - RELEASE_TAG_VERSION=$(echo $CI_COMMIT_TAG | sed -n "s/rel_//p")