Revert "Revert "msm: hotplug: wait for hotplug completion event from secondary core""

This reverts commit fe0177450921b64dfc8c241f481d3068c72ca87c

Change-Id: I89cdc2397f3128098932809f4c54b665428ea0ea
Merge "Revert "Revert "msm: hotplug: wait for hotplug completion event from secondary core""" into jellybean-mr1