arm/dt: msm8226: Create device tree for camera on MTP

GPIO standby pin for back and front camera are different for 8226 MTP
and other variants of 8226 (CDP / QRD). Create new dtsi file for
8226 MTP for camera to handle this and include in proper mtp dts file.

Change-Id: Iceb47932ed7b9a809f4912b6d2994cbcbcce8813
Signed-off-by: Sreesudhan Ramakrish Ramkumar <srramku@codeaurora.org>