msm: camera: Add shared gpio and flash support

Add a driver to support shared gpio and shared flash
for dual camera device.
Sometimes, the device will share same pins/flash between
two different cameras, and the cameras need to be opened
at same time. So, add shared resource manager driver to
support shared gpio and flash.

Change-Id: I93ad91d505fa3383706435cc2c61f8e242803649
Signed-off-by: Depeng Shao <depengs@codeaurora.org>