MAINTAINERS: update drm git tree entry

Fix Dave's git tree.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

MAINTAINERS

@@ -2845,7 +2845,7 @@ F:	lib/kobj*
 DRM DRIVERS
 M:	David Airlie <airlied@linux.ie>
 L:	dri-devel@lists.freedesktop.org
-T:	git git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6.git
+T:	git git://people.freedesktop.org/~airlied/linux
 S:	Maintained
 F:	drivers/gpu/drm/
 F:	include/drm/