platform: msm_shared: Fix reboot module

Fix reboot module to write reboot reason to PON register instead imem
cookie when PON registers usage is enabled, use REG_READ/REG_WRITE
macros for pmic-spmi read & writes, add shutdown_device API, use pmic
reboot APIs from target as the pmic reboot code changes based on the
pmic used for the target and remove unwanted header file inclusion.
Move the compilation of rpmb to the to end of the rules.mk otherwise
all the files below would be considered as part of rpmb module and
results in compilation error

Change-Id: I7ed4b213f42b1e3e49dd7b9b7fa56d37fd7db03e
5 files changed