Fix race condition in backlight adjustment.

When configuring the automatic backlight levels, there's a race
condition in setting the lux and brightness settings as the settings
provider doesn't allow storing multiple settings atomically. When
deleting rows, there's quite a high chance of DisplayPowerController
picking up a state where the lux values already have the lower number of
rows, but the brightness values do not, effectively leading to an
ArrayIndexOutOfBoundsException.

Fix that by
- waiting a second of cool-down time until applying the settings and
- adding a sanity check for the very unlikely case that the delay
  between writing both values is > 1 second

Change-Id: I44e41530fc5334aaefc4ab7d3a90542f78fabe0c
JIRA:CYAN-755
hwui: This code should only be enabled with QCOM_BSP

 * Crashy crashy!

Change-Id: I1a06ac54a8ce2dccbf4a67424b0cbb6e7dd21e8b
Merge "Fix race condition in backlight adjustment." into jb-mr1
Merge remote-tracking branch 'upstream/jb-mr1' into jb-mr1