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
diff --git a/platform/msm_shared/scm.c b/platform/msm_shared/scm.c
index bccdb3d..2dda14e 100644
--- a/platform/msm_shared/scm.c
+++ b/platform/msm_shared/scm.c
@@ -62,7 +62,7 @@
 	return scm_arm_support;
 }
 
-static int is_scm_call_available(uint32_t svc_id, uint32_t cmd_id)
+int is_scm_call_available(uint32_t svc_id, uint32_t cmd_id)
 {
 	int ret;
 	scmcall_arg scm_arg = {0};