drm/komeda: Add komeda_crtc_funcs

Added functions:
-  komeda_crtc_reset
-  komeda_crtc_vblank_enable
-  komeda_crtc_vblank_disable

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