led: Enable led in 88pm860x

Enable led sub device in Marvell 88PM860x. Two LED arrays can be supported.
Each LED array can be used for R,G,B leds.

Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>