drm/amd: add some extra checks that is_dig_enabled is defined

There are a few places that this isn't checked that could potentially
be a NULL pointer access.
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/clk_mgr/dcn21/rn_clk_mgr.c

@@ -77,7 +77,8 @@ int rn_get_active_display_cnt_wa(
 		const struct dc_link *link = dc->links[i];
 
 		/* abusing the fact that the dig and phy are coupled to see if the phy is enabled */
-		if (link->link_enc->funcs->is_dig_enabled(link->link_enc))
+		if (link->link_enc->funcs->is_dig_enabled &&
+		    link->link_enc->funcs->is_dig_enabled(link->link_enc))
 			display_count++;
 	}
 

drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c

@@ -1827,17 +1827,16 @@ void dce110_enable_accelerated_mode(struct dc *dc, struct dc_state *context)
 			if (edp_link != edp_streams[0]->link)
 				continue;
 			// enable fastboot if backend is enabled on eDP
-			if (edp_link->link_enc->funcs->is_dig_enabled(edp_link->link_enc)) {
-				/* Set optimization flag on eDP stream*/
-				if (edp_link->link_status.link_active) {
-					edp_stream = edp_streams[0];
-					can_apply_edp_fast_boot = !is_edp_ilr_optimization_required(edp_stream->link, &edp_stream->timing);
-					edp_stream->apply_edp_fast_boot_optimization = can_apply_edp_fast_boot;
-					if (can_apply_edp_fast_boot)
-						DC_LOG_EVENT_LINK_TRAINING("eDP fast boot disabled to optimize link rate\n");
-
-					break;
-				}
+			if (edp_link->link_enc->funcs->is_dig_enabled &&
+			    edp_link->link_enc->funcs->is_dig_enabled(edp_link->link_enc) &&
+			    edp_link->link_status.link_active) {
+				edp_stream = edp_streams[0];
+				can_apply_edp_fast_boot = !is_edp_ilr_optimization_required(edp_stream->link, &edp_stream->timing);
+				edp_stream->apply_edp_fast_boot_optimization = can_apply_edp_fast_boot;
+				if (can_apply_edp_fast_boot)
+					DC_LOG_EVENT_LINK_TRAINING("eDP fast boot disabled to optimize link rate\n");
+
+				break;
 			}
 		}
 		// We are trying to enable eDP, don't power down VDD