lisa/_assets/kmodules/lisa: Make in-tree imports match mainline

Adjust headers imported during in-tree builds to match new mainline
kernels rather than older product kernels.
This will avoid build errors on newer kernels.

Additionally, add a documentation note about kernel tree commits
providing necessary import guards.

Signed-off-by: Kajetan Puchalski <kajetan.puchalski@arm.com>