kernel-yocto: ensure sccs variable is set when using KBUILD_DEFCONFIG
When using KBUILD_DEFCONFIG, $sccs should be set to the $WORKDIR/defconfig
regardless if it compares or is copied. Otherwise $sccs is not set and the
defconfig is not found correctly.
Part of
[YOCTO #12162]
Signed-off-by: Saul Wold <sgw@linux.intel.com> Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>