ARM: dts: Correct audio input route & set mic bias for am335x-pepper

Audio-in was incorrectly routed to Line In. It should be Mic3L as per
schematic.

Using mic-bias voltage at 2.0v (<0x1>) does not work for some reason. There
is no voltage seen on micbias (R127). Mic-bias voltage of 2.5v (<0x2>) works.
I see voltage of 2.475v across GND and micbias.

With these changes, I can record audio with a pair of proliferate TRRS earbuds.

Signed-off-by: Adam YH Lee <adam.yh.lee@gmail.com>
Acked-by: Ash Charles <ashcharles@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am335x-pepper.dts

@@ -74,6 +74,7 @@
 	audio_codec: tlv320aic3106@1b {
 		compatible = "ti,tlv320aic3106";
 		reg = <0x1b>;
+		ai3x-micbias-vg = <0x2>;
 	};
 
 	accel: lis331dlh@1d {
@@ -153,7 +154,7 @@
 	ti,audio-routing =
 		"Headphone Jack",	"HPLOUT",
 		"Headphone Jack",	"HPROUT",
-		"LINE1L",		"Line In";
+		"MIC3L",		"Mic3L Switch";
 };
 
 &mcasp0 {