When being in dark environments, turning screen off, then moving to
bright environments and turning screen on, sometimes it happens that the
light sensor emits an initial light sample of 1 lux, which causes the
automatic brightness controller to ramp down the brightness even though
the ambient brightness is high. Avoid the controller using those samples
by giving the light sensor some time to warm up.
Change-Id: I81dcb41a25ff0c9f0cf3265da7054ac7ebcbcc34
0b368e57b4