Make dmix card-specific

The parameters of dmix PCM definition are now card-specific.
As default, period_size = 1024 and periods = 8 are used.

src/conf/alsa.conf

@@ -186,30 +186,6 @@ pcm.plug {
 	slave.pcm $SLAVE
 }
 
-pcm.dmix {
-	@args [ SLAVE FORMAT RATE ]
-	@args.SLAVE {
-		type string
-		default "hw:0,0"
-	}
-	@args.FORMAT {
-		type string
-		default S16_LE
-	}
-	@args.RATE {
-		type integer
-		default 48000
-	}
-	type dmix
-	ipc_key 5678293
-	ipc_key_add_uid yes
-	slave {
-		pcm $SLAVE
-		format $FORMAT
-		rate $RATE
-	}
-}
-
 pcm.dsnoop {
 	@args [ SLAVE FORMAT RATE ]
 	@args.SLAVE {
@@ -299,7 +275,9 @@ pcm.surround71 cards.pcm.surround71
 pcm.iec958 cards.pcm.iec958
 pcm.spdif cards.pcm.iec958
 pcm.modem cards.pcm.modem
+
 pcm.default cards.pcm.default
+pcm.dmix cards.pcm.dmix
 
 #
 #  Control interface