drm/amd/display: use encoder's engine id to find matched free audio device

[Why]
On some platforms, the encoder id 3 is not populated. So the encoders
are not stored in right order as index (id: 0, 1, 2, 4, 5) at pool. This
would cause encoders id 4 & id 5 to fail when finding corresponding
audio device, defaulting to the first available audio device. As result,
we cannot stream audio into two DP ports with encoders id 4 & id 5.

[How]
It need to create enough audio device objects (0 - 5) to perform matching.
Then use encoder engine id to find matched audio device.
Signed-off-by: Tai Man <taiman.wong@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -258,7 +258,7 @@ bool resource_construct(
 		 * PORT_CONNECTIVITY == 1 (as instructed by HW team).
 		 */
 		update_num_audio(&straps, &num_audio, &pool->audio_support);
-		for (i = 0; i < pool->pipe_count && i < num_audio; i++) {
+		for (i = 0; i < caps->num_audio; i++) {
 			struct audio *aud = create_funcs->create_audio(ctx, i);
 
 			if (aud == NULL) {
@@ -1669,6 +1669,12 @@ static struct audio *find_first_free_audio(
 			return pool->audios[i];
 		}
 	}
+
+    /* use engine id to find free audio */
+	if ((id < pool->audio_count) && (res_ctx->is_audio_acquired[id] == false)) {
+		return pool->audios[id];
+	}
+
 	/*not found the matching one, first come first serve*/
 	for (i = 0; i < pool->audio_count; i++) {
 		if (res_ctx->is_audio_acquired[i] == false) {