kernel-build: Mount and run in $WORKSPACE not $HOME

When running docker we bind mount and run in $HOME, but that only
works if $WORKSPACE is under $HOME. Instead we can just bind mount and
run in $WORKSPACE.

Change-Id: I872621fc7d92c5b6721e77e2a3048c41b14d9529
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/kernel-build.sh b/kernel-build.sh
index b278368..5cc4723 100755
--- a/kernel-build.sh
+++ b/kernel-build.sh
@@ -94,7 +94,7 @@
 
 # Run the docker container, execute the build script we just built
 docker run --cap-add=sys_admin --net=host --rm=true -e WORKSPACE=${WORKSPACE} --user="${USER}" \
-  -w "${HOME}" -v "${HOME}":"${HOME}" -t linux-build/ubuntu ${WORKSPACE}/build.sh
+  -w "${WORKSPACE}" -v "${WORKSPACE}":"${WORKSPACE}" -t linux-build/ubuntu ${WORKSPACE}/build.sh
 
 result=${?}