ARM: dts: refactor Odroid DTS file and add support for Odroid X2 and U2/U3

This patch moves some parts of exynos4412-odroidx.dts to common
exynos4412-odroid-common.dtsi file and adds support for Odroid X2 and
U2/U3 boards. X2 is same as X, but it has faster SoC module (1.7GHz
instead of 1.4GHz), while U2/U3 differs from X2 by different way of
routing signals to host USB hub. It also lacks some hw modules not yet
supported by those dts files (i.e. LCD & touch panel).

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>