drm/radeon/kms: release AGP bridge at suspend

I think it's good to release the AGP bridge at suspend
and reacquire it at resume. Also fix :
https://bugzilla.kernel.org/show_bug.cgi?id=15969

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_agp.c b/drivers/gpu/drm/radeon/radeon_agp.c
index 28e473f..f40dfb7 100644
--- a/drivers/gpu/drm/radeon/radeon_agp.c
+++ b/drivers/gpu/drm/radeon/radeon_agp.c
@@ -270,3 +270,8 @@
 	}
 #endif
 }
+
+void radeon_agp_suspend(struct radeon_device *rdev)
+{
+	radeon_agp_fini(rdev);
+}