ARM: dts: msm: add camera focus and snapshot nodes for MSMFALCON

MSM GPIO 64 is connected to Camera Focus Button and MSM GPIO 113 is
connected to Camera Snapshot Button. Add the nodes for these buttons
along with their pintrl configuration.

Change-Id: Ifc03c72233dcf1081fc3f2fed495d19e48bb8c7d
Signed-off-by: Himanshu Aggarwal <haggarwa@codeaurora.org>