MAINTAINERS: maintain drm/arm drivers in drm-misc for now

From discussions with Liviu it sounded like the komeda team would
benefit a bit from more cross-review with other drivers. To make sure
komeda is aligned with how similar problems are solved in other
drivers (in the end everyone ends up with similar ideas on how to
solve various display engine design issues).

An option would be to use drm-misc as an incubator for a few kernel
releases, at least until the big design items have been tackled: Aside
from the four kms properties already landed that we need to take out
again there's also a pile of new ones proposed already for komeda.
drm-misc seems to work fairly well at encouraging these kind of
cross-driver reviews and working on cross-driver infrastructure in drm
core. Later on we can move all the drivers out to a dedicated arm tree
again (if that's desired).

Of coures that would mean Lowry and James need drm-misc commit rights
(all other arm contributors have it already I think).

Cc: Lowry Li (Arm Technology China) <lowry.li@arm.com>
Cc: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Mali DP Maintainers <malidp@foss.arm.com>
Cc: Brian Starkey <brian.starkey@arm.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: Sean Paul <sean@poorly.run>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190705121006.26085-5-daniel.vetter@ffwll.ch