ARM: dts: msm: add gpio-keys device node

Add gpio based keys device node to msmferrum CDP and MTP.
The supported keys are VOLUME UP, CAMERA SNAPSHOT and
CAMERA FOCUS. Also add the gpio-keys active and suspend
settings as per the pinctrl framework.

Change-Id: I81d96bb13ea848af2d9268e88ccd82c3175a110d
Signed-off-by: Himanshu Aggarwal <haggarwa@codeaurora.org>