ARM: dts: Add board dts file for ODROID-X

Add initial DT for Hardkernel's ODROID-X board based on EXYNOS4412
SoC. This patch including adds the node to support fixed voltage for
peripherals like LED, ethernet controller, and this patch adds GPIO
connected LEDS on ODROID-X board and configure its properties like
following:
LED1: use 'heartbeat' trigger, blinking while the board is running.
LED2: use 'mmc0' trigger, on when mmc0 is accessing.

And adds the device node to support eMMC storage on SDCARD4 ports,
controlled by MSHC.

Signed-off-by: Dongjin Kim <tobetter@gmail.com>
Acked-by: Olof Johansson <olof@lixom.net>
[kgene.kim@samsung.com: squashed into one commit as per Olof's comment]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>