drm/amd/display: Added Check For dc->res_pool

[WHY]
-To ensure dc->res_pool has been initialized

[HOW]
-Check if dc->res_pool is true in
the if statement
Reviewed-by: Martin Leung <Martin.Leung@amd.com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@amd.com>
Signed-off-by: Jarif Aftab <jaraftab@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc.c

@@ -809,7 +809,7 @@ void dc_stream_set_static_screen_params(struct dc *dc,
 static void dc_destruct(struct dc *dc)
 {
 	// reset link encoder assignment table on destruct
-	if (dc->res_pool->funcs->link_encs_assign)
+	if (dc->res_pool && dc->res_pool->funcs->link_encs_assign)
 		link_enc_cfg_init(dc, dc->current_state);
 
 	if (dc->current_state) {