drm/amd/display: Fix null reference to state when getting subvp type

[WHY&HOW]
Need to provide valid pointer to dc_state when getting subvp pipe type.
Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Dillon Varone <dillon.varone@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c

@@ -2333,7 +2333,7 @@ void dcn10_enable_timing_synchronization(
 	}
 
 	for (i = 1; i < group_size; i++) {
-		if (dc_state_get_pipe_subvp_type(NULL, grouped_pipes[i]) == SUBVP_PHANTOM)
+		if (dc_state_get_pipe_subvp_type(state, grouped_pipes[i]) == SUBVP_PHANTOM)
 			continue;
 
 		opp = grouped_pipes[i]->stream_res.opp;