archiver.bbclass: Fix --runall=deploy_archives for images

Fixed:
INHERIT += "archiver"
COPYLEFT_LICENSE_INCLUDE = "*"

$ bitbake core-image-minimal --runall=deploy_archives
[snip]
KeyError: '/path/to/meta/recipes-core/images/core-image-minimal.bb:do_ar_original'
[snip]

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>