msm: subsystem_restart: Move device tree parsing code into the framework

Every driver has to repeat the code for parsing device tree nodes for the
SMP2P gpios. So, move this parsing code into the framework level to avoid
this duplication of code.

Change-Id: Ie27a5f37ce2b9718a5cc0ccf11c7abda1c6cb1df
Signed-off-by: Seemanta Dutta <seemanta@codeaurora.org>