Add limitations to HDR.

1. Only allow HDR if HDR takes up more than 50% of the screen.
2. Scale normal brightness range to HDR levels. To do this, we now keep
the normal brightness range when HDR is enabled and scale the brightness
value to the higher HBM range. This allows HDR to scale as it did
previous as well as function as expected when automatic-brightness is
off.
3. Add more logging to HBMController dumpsys.

Bug: 187804126
Bug: 188479946
Bug: 189384189
Test: atest com.android.server.display
Change-Id: I515a9ee7ca16bcf8070b1cdab09943b68f038949