drm/komeda: Expose bus_width to Komeda-CORE

CHIP set bus_width according to the HW configuration, and CORE will use
it as buffer alignment.

v2: Rebase

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