MAINTAINERS: update radeon entry to include amdgpu as well

Both are maintained by same team.

Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index c647c40e..20166fb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3712,7 +3712,7 @@
 F:	include/drm/
 F:	include/uapi/drm/
 
-RADEON DRM DRIVERS
+RADEON and AMDGPU DRM DRIVERS
 M:	Alex Deucher <alexander.deucher@amd.com>
 M:	Christian König <christian.koenig@amd.com>
 L:	dri-devel@lists.freedesktop.org
@@ -3720,6 +3720,8 @@
 S:	Supported
 F:	drivers/gpu/drm/radeon/
 F:	include/uapi/drm/radeon*
+F:	drivers/gpu/drm/amd/
+F:	include/uapi/drm/amdgpu*
 
 DRM PANEL DRIVERS
 M:	Thierry Reding <thierry.reding@gmail.com>