Add new bucket above high brightness for "sunlight".

Being in direct sunlight can cause the screen to look like it's
"strobing", so we want to tell the kernel when we think we're in this
state so it can configure the display to avoid this effect.

Bug: 63820596
Test: TBD
Change-Id: Ie0b7a8d45d080231748337507d1037ab45950aed