phy: Add Exynos 5250 support to the Exynos USB 2.0 PHY driver

Add support for Exynos 5250. This driver is to replace the old
USB 2.0 PHY driver.

Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>