MAINTAINERS: Add Dmitry as MSM DRM driver co-maintainer

For the past several releases I have been assisting Rob by writing,
collecting, testing and integrating patches for non-GPU and non-core
parts of MSM DRM driver, while Rob is more interested in improving the
GPU-related part. Let's note this in the MAINTAINERS file.

While we are at it, per Rob's suggestion let's also promote Abhinav
Kumar to M: (as he is actively working on the driver) and switch Sean
Paul to R: (since he isn't doing much on msm these days).
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Rob Clark <robdclark@gmail.com>
Link: https://lore.kernel.org/r/20220429215324.3729441-1-dmitry.baryshkov@linaro.orgSigned-off-by: Rob Clark <robdclark@chromium.org>

MAINTAINERS

@@ -6254,8 +6254,9 @@ F:	drivers/gpu/drm/tiny/panel-mipi-dbi.c
 
 DRM DRIVER FOR MSM ADRENO GPU
 M:	Rob Clark <robdclark@gmail.com>
-M:	Sean Paul <sean@poorly.run>
-R:	Abhinav Kumar <quic_abhinavk@quicinc.com>
+M:	Abhinav Kumar <quic_abhinavk@quicinc.com>
+M:	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
+R:	Sean Paul <sean@poorly.run>
 L:	linux-arm-msm@vger.kernel.org
 L:	dri-devel@lists.freedesktop.org
 L:	freedreno@lists.freedesktop.org