SF backdoor for primary display hotplug

This is a backdoor for SurfaceFlinger which injects a hotplug
event for the primary display. This causes SF to deallocate and
reallocate the  display state including framebuffers. From the
user perspective this should look like a noop because HWC will
return the same display properties.

Bug: 167670568
Test: adb shell service call SurfaceFlinger 1037
Change-Id: Ie52aac67571ed41c1a796797b7d7c54bcbdd9bdc