Fix configuration for Aureon and Prodigy71 boards

Fixed the default configuration of Aureon and Prodigy71 boards
to use dmix/dsnoop.  Added a new alias for Prodigy71LT.

src/conf/cards/Aureon51.conf

@@ -2,6 +2,29 @@
 # Configuration for the Aureon51 (Envy24HT) chip
 #
 
+# default with dmix & dsnoop
+Aureon51.pcm.default {
+	@args [ CARD ]
+	@args.CARD {
+		type string
+	}
+	type asym
+	playback.pcm {
+		type plug
+		slave.pcm {
+			@func concat
+			strings [ "dmix:" $CARD ",FORMAT=S32_LE" ]
+		}
+	}
+	capture.pcm {
+		type plug
+		slave.pcm {
+			@func concat
+			strings [ "dsnoop:" $CARD ",FORMAT=S32_LE" ]
+		}
+	}
+}
+
 <confdir:pcm/front.conf>
 
 Aureon51.pcm.front.0 {