backlight: add generic version of o2micro pwm-based backlight driver

Used on the Kindle Fire HD 8.9", this version allows for a wider range
of configuration via platform data.

Change-Id: I5525ef340750b4cd201830408f2d7d18599e6321
panel-backlight: change from omap-pwm led driver to o2micro backlight driver

Change-Id: I61e561f55151e1291144c72f4e5914b93ba6cf73
leds: remove omap-pwm driver

Change-Id: Iebce5d279b7d7d76fc4d3f74da4fd2c11f0d83d6
defconfig: update for backlight changes

Change-Id: I3de52bb7356e417ea5129ce540b4d6b473b6a489