platform: msm_shared: Wait for smd channel to be closed.

Appsbl sends channel close signal to rpm and jumps to hlos
without waiting for the channel to be actually closed.
Due to this hlos fails to communicate to rpm over the same
channel. To ensure a proper hand-off make sure to wait for
RPM-SMD channel to be closed before jumping to hlos.

Change-Id: I59efd38b52ef704e97a5e4abf7d2e507e6c7efb9
1 file changed