ARM: mach-shmobile: mackerel: add ak4642 amixer settings on comment

current ak4642 needs amixer settings for playing which was not
needed on old kernel.
This patch show it on comment area
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

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

@@ -192,6 +192,16 @@
  *
  */
 
+/*
+ * FSI - AK4642
+ *
+ * it needs amixer settings for playing
+ *
+ * amixer set "Headphone" on
+ * amixer set "HPOUTL Mixer DACH" on
+ * amixer set "HPOUTR Mixer DACH" on
+ */
+
 /*
  * FIXME !!
  *