leds: LED driver for TI LP3952 6-Channel Color LED

The chip can drive 2 sets of RGB leds. Controller can
be controlled via PWM, I2C and audio synchronisation.
This driver uses I2C to communicate with the chip.

Datasheet: http://www.ti.com/lit/gpn/lp3952



Signed-off-by: Tony Makkiel <tony.makkiel@daqri.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>