arm/dt: msm8610: Enable GPIO Keys

Enable GPIO key support to device tree for camera
snapshot, camera focus and volume up keys.

Change-Id: Idde5c9e7d4db99e165313636b9c4a316516dd802
Acked-by: Chun Zhang <chunz@qti.qualcomm.com>
Signed-off-by: Amy Maloche <amaloche@codeaurora.org>