kernel-yocto: improve metadata patching

kernel-yocto: improve metadata patching

The ability to patch the kernel-yocto metadata was added to support
debug and easier test cycles on kernel-cache provided fragments. As
such, it was very simple and has limited functionality.

That being said, it is an available feature and can be improved to
handle patches that fail to apply.

The main kernel patching is already handled by the kern-tools, so
we extend the patching of the meta-data to same tools and inherit
more functinality from the scripts.

[YOCTO #15266]

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