ARM: dts: am335x-pepper: Fix the audio CODEC's reset pin

The correct DT property for specifying a GPIO used for reset
is "reset-gpios", fix this here.

Fixes: 4341881d

 ("ARM: dts: Add devicetree for Gumstix Pepper board")

Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>