msm: rpc: add shutdown and restart handler for rpc

Add shutdown and restart handler for rpcrouter. The
shutdown handler will take care of calling the
msm_rpcrouter_close function with a pre defined
priority. PM no longer had to handle rpc in the shutdown/reboot
sequence.

Signed-off-by: Angshuman Sarkar <angshuman@codeaurora.org>
(cherry picked from commit 4e253c2c596ff611556736822a6df166132504e7)

Signed-off-by: Gopal Goberu <ggober@codeaurora.org>

Conflicts:
	arch/arm/mach-msm/restart_7k.c

Change-Id: I43400152a260e3cc73a7b73ca547296255705d7a