image/rm_work: Promote do_image_complete to be more sstate like
We relied on the missing do_image_complete_setscene task to ensure the dummy
sstate tarball that was created would never be used. This lead to its own
issues and a better fix for SSTATE_SKIP_CREATION has now been merged.
We can therefore make do_image_complete look like a more standard sstate
task which means image generation doesn't keep rerunning when using rm_work.
We do need to turn do_image_complete's stamp into an sstate version to
handle this (it otherwise matches the do_image_* glob).
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
