ARM: EXYNOS: Add usb otg phy control for EXYNOS4210

This patch supports to control usb otg phy of EXYNOS4210.

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
[Rebased on the newest git/kgene/linux-samsung #for-next]
Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
[kgene.kim@samsung.com: squashed 2 patches together]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>