MAINTAINERS: Add entry for DRM panel drivers

Add myself as the maintainer for DRM panel drivers. The plan is to
collect panel-related patches in one place to reduce conflicts and
unburden Dave.

Signed-off-by: Thierry Reding <[e-mail]>

MAINTAINERS

···
 F:	include/drm/
 F:	include/uapi/drm/
 
+DRM PANEL DRIVERS
+M:	Thierry Reding <[e-mail]>
+L:	[e-mail]
+T:	git git://anongit.freedesktop.org/tegra/linux.git
+S:	Maintained
+F:	drivers/gpu/drm/drm_panel.c
+F:	drivers/gpu/drm/panel/
+F:	include/drm/drm_panel.h
+F:	Documentation/devicetree/bindings/panel/
+
 INTEL DRM DRIVERS (excluding Poulsbo, Moorestown and derivative chipsets)
 M:	Daniel Vetter <[e-mail]>
 M:	Jani Nikula <[e-mail]>