This helps validating DTS files.

Introduced changes:
1. Added arm-gic.h include
Signed-off-by: NRafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20210713093155.1752-1-zajec5@gmail.comSigned-off-by: NRob Herring <robh@kernel.org>