leds: lp8860: Various fixes to align with LED framework
Update the driver to conform with the LED framework:
- use devm_led_classdev_register
- destroy mutex on exit
- remove dependency on CONFIG_OF in the driver and move
to the Kconfig
- update the MODULE_LICENSE to GPL v2
- remove setting of MAX brightness as the LED framework
does this.
Signed-off-by: Dan Murphy <dmurphy@ti.com> Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>