Use dmix/dsnoop for default PCM

Use dmix/dsnoop plugins for default PCM in most of mobo chips

src/conf/cards/CMI8338.conf

@@ -14,6 +14,29 @@ CMI8338.pcm.front.0 {
 	device 0
 }	
 
+# default with dmix/dsnoop
+CMI8338.pcm.default {
+	@args [ CARD ]
+	@args.CARD {
+		type integer
+	}
+	type asym
+	playback.pcm {
+		type plug
+		slave.pcm {
+			@func concat
+			strings [ "dmix:" $CARD ]
+		}
+	}
+	capture.pcm {
+		type plug
+		slave.pcm {
+			@func concat
+			strings [ "dsnoop:" $CARD ]
+		}
+	}
+}
+
 <confdir:pcm/rear.conf>
 
 # 2nd DAC