MAINTAINERS: Fix pattern for Documentation path for Arm Mali Komeda

The Device Tree bindings documentation file is in a simplified path
that doesn't match the MAINTAINERS entry.

Reported-by: Joe Perches <joe@perches.com>
Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>