phy: Add new Exynos5 USB 3.0 PHY driver

Add a new driver for the USB 3.0 PHY on Exynos5 series of SoCs.
The new driver uses the generic PHY framework and will interact
with DWC3 controller present on Exynos5 series of SoCs.

Also, created a new header file in linux/mfd/syscon/ for
Exynos5 SoCs and put the required PMU offset definitions
for the basic available PHYs.

Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>