kernel-yocto: account for extracted defconfig in elements check

kernel-yocto: account for extracted defconfig in elements check

The test for whether or not scc should to invoked to generate a
config.queue was missing the newly created sccs_defconfig variable.
We need to test for that variable as well, or we may miss generating
the config.queue in some cases.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>