ARM: dts: add max77686 node entry for ODROID-X

ODROID-X board have a max77686 PMIC on i2c channel 0. The properties of used
LDO and BUCK are defined according the schematic.

Signed-off-by: Dongjin Kim <tobetter@gmail.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>