MAINTAINERS: add entry for drm radeon driver

Add an entry for radeon.
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

MAINTAINERS

@@ -2851,6 +2851,16 @@ F:	drivers/gpu/drm/
 F:	include/drm/
 F:	include/uapi/drm/
 
+RADEON DRM DRIVERS
+M:	Alex Deucher <alexander.deucher@amd.com>
+M:	Christian König <christian.koenig@amd.com>
+L:	dri-devel@lists.freedesktop.org
+T:	git git://people.freedesktop.org/~agd5f/linux
+S:	Supported
+F:	drivers/gpu/drm/radeon/
+F:	include/drm/radeon*
+F:	include/uapi/drm/radeon*
+
 INTEL DRM DRIVERS (excluding Poulsbo, Moorestown and derivative chipsets)
 M:	Daniel Vetter <daniel.vetter@ffwll.ch>
 M:	Jani Nikula <jani.nikula@linux.intel.com>