ARM: EXYNOS: Enable XHCI support on exynos5

This patch enables support for XHCI on exynos5 series of SOCs,
to support host side USB 3.0 support.

Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>