drm/radeon/kms: initialize set_surface_reg reg for rs600 asic

rs600 asic was missing set_surface_reg callback leading to
oops.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_asic.h

@@ -407,6 +407,8 @@ static struct radeon_asic rs600_asic = {
 	.get_pcie_lanes = NULL,
 	.set_pcie_lanes = NULL,
 	.set_clock_gating = &radeon_atom_set_clock_gating,
+	.set_surface_reg = r100_set_surface_reg,
+	.clear_surface_reg = r100_clear_surface_reg,
 	.bandwidth_update = &rs600_bandwidth_update,
 	.hpd_init = &rs600_hpd_init,
 	.hpd_fini = &rs600_hpd_fini,