fix(coreos-base/bootengine) update 9999 ebuild so that cros_workon works

This was broken due to the changes in the "stable" bootengine package
and I forgot to update this version as well, sorry.
Merge pull request #89 from gregkh/boot_kernel_update

fix(coreos-base/bootengine) update 9999 ebuild so that cros_workon works