aemfvp-a-rme: locate container script

docker container script is needed to rebuild the buildroot stack
needed during automated cca kernel update. modifying the path of
execution script to locate it in parent dir.

Signed-off-by: nitin sharma <nitin.sharma3@arm.com>
Change-Id: I9e72dcfef11c4dbb3c6315a14685151d8115561c