[oe] DEPLOY_DIR and package_stagefile_shell

[George C. Huntington, III]

It appears that if you override DEPLOY_DIR to make the DEPLOY directory
outside of TMPDIR, then recipes that call package_stagefile_shell fail. the
sed magic in package_stagefile_shell assumes that the path will be in
TMPDIR.  Should the package_stagefile_shell be fixed, or should the recipes
that call it with ${DEPLOY_DIR_IMAGE} be changed.  the u-boot.inc and the
linux.inc have this problem.