SF: Log hotplug events

When debugging hotplug related issues it is very useful to have
hotplug events in the logs. These events occur rarely so the
overhead of this additional log is low.

Bug: 174644816
Test: adb logcat | grep onHotplug
Change-Id: If1383a4dea2e95060fa3c4332406b80fc42af40c
1 file changed