MAINTAINERS: Update GPU Scheduler email

Update GPU Scheduler maintainer email.

Cc: Alex Deucher <Alexander.Deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@gmail.com>
Cc: AMD Graphics <amd-gfx@lists.freedesktop.org>
Cc: Direct Rendering Infrastructure - Development <dri-devel@lists.freedesktop.org>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <Alexander.Deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/508985/

Author: Luben Tuikov

MAINTAINERS

@@ -7113,7 +7113,7 @@ F:	drivers/gpu/drm/ttm/
 F:	include/drm/ttm/
 
 DRM GPU SCHEDULER
-M:	Andrey Grodzovsky <andrey.grodzovsky@amd.com>
+M:	Luben Tuikov <luben.tuikov@amd.com>
 L:	dri-devel@lists.freedesktop.org
 S:	Maintained
 T:	git git://anongit.freedesktop.org/drm/drm-misc