ARM: shmobile: add sample amixer settings for armadillo800eva

wm8978 codec requires amixer settings for capture.
This patch adds sample amixer settings on comment area.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/mach-shmobile/board-armadillo800eva.c

@@ -124,6 +124,14 @@
  * this command is required when playback.
  *
  * # amixer set "Headphone" 50
+ *
+ * this command is required when capture.
+ *
+ * # amixer set "Input PGA" 15
+ * # amixer set "Left Input Mixer MicP" on
+ * # amixer set "Left Input Mixer MicN" on
+ * # amixer set "Right Input Mixer MicN" on
+ * # amixer set "Right Input Mixer MicP" on
  */
 
 /*