build-setup: Mount ${WORKSPACE} while building openbmc
build-setup: Mount ${WORKSPACE} while building openbmc

The build.sh script is created in host's ${WORKSPACE}, and executed in
docker container. If it's not available in the docker container, it
fails to execute the script by below error.

 no such file or directory

Mount it in the docker container so that it is guaranteed to be avaialbe
in the container.

Tested: Verify the ${WORKSPACE} is mounted if it's not in ${HOME}, and
        the build runs OK.

Signed-off-by: Lei YU <fc52a17c06c071ee7cd115c972235443e2107013@bytedance.com>
Change-Id: Id459410249c90688e683db63073b36a9959a97aa

openbmc/openbmc-build-scripts,openbmc/openbmc-build-scripts