drm/komeda: Add komeda_framebuffer

komeda_framebuffer is for extending drm_framebuffer to add komeda own
attributes and komeda specific fb handling.

Changes in v3:
- Fixed style problem found by checkpatch.pl --strict.

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