drm/doc: Add initial komeda driver documentation

v2: Some editing changes according to Randy Dunlap's comments
Signed-off-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

Documentation/gpu/drivers.rst

@@ -18,6 +18,7 @@ GPU Driver Documentation
    bridge/dw-hdmi
    xen-front
    afbc
+   komeda-kms
 
 .. only::  subproject and html