mfd: Adopt mfd_data in 88pm860x led

Copy 88pm860x platform data into different mfd_data structure for
led driver. So move the identification of device node from led
driver to mfd driver.

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