kern-tools: avoid duplicate .scc file processing

kern-tools: avoid duplicate .scc file processing

With the recent changes to improve patch processing times, the ability
to skip already applied patches is not active by default.

The automatic detection and resume was hiding issues with the include
files generated by scripts like yocto-bsp.

If a .scc file that contains a patch is included twice, the patch is
applied twice, and the second appliation fails for obvious reasons.

We can partially fix this by ensuring that already included
configuration fragments are not forced into the meta-series.

.scc files that are explicitly listed twice will continue to fail, and
recipes must be modified to avoid this.

[YOCTO: #8486]

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