drm/amd/display: Use helper for determining HDMI signal

Use helper to determine if HDMI signal when processing avmute.
Signed-off-by: NEric Bernstein <eric.bernstein@amd.com>
Reviewed-by: NCharlene Liu <Charlene.Liu@amd.com>
Acked-by: NLeo Li <sunpeng.li@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -2860,7 +2860,7 @@ void core_link_set_avmute(struct pipe_ctx *pipe_ctx, bool enable)
 {
 	struct dc  *core_dc = pipe_ctx->stream->ctx->dc;
 
-	if (pipe_ctx->stream->signal != SIGNAL_TYPE_HDMI_TYPE_A)
+	if (!dc_is_hdmi_signal(pipe_ctx->stream->signal))
 		return;
 
 	core_dc->hwss.set_avmute(pipe_ctx, enable);