drm/amd/display: Use helper function to check for HDMI signal

[How]
Use dc_is_hdmi_signal to determine signal type.
Signed-off-by: NJinZe.Xu <JinZe.Xu@amd.com>
Reviewed-by: NCharlene Liu <Charlene.Liu@amd.com>
Acked-by: NAurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -3282,7 +3282,7 @@ void core_link_disable_stream(struct pipe_ctx *pipe_ctx)
 			dc_is_virtual_signal(pipe_ctx->stream->signal))
 		return;
 
-	if (pipe_ctx->stream->signal == SIGNAL_TYPE_HDMI_TYPE_A) {
+	if (dc_is_hdmi_signal(pipe_ctx->stream->signal)) {
 		core_link_set_avmute(pipe_ctx, true);
 	}