phy: Add support for S5PV210 to the Exynos USB 2.0 PHY driver

Add support for the Samsung's S5PV210 SoC to the Exynos USB 2.0 PHY driver.

Signed-off-by: Mateusz Krawczuk <m.krawczuk@partner.samsung.com>
[k.debski@samsung.com: cleanup and commit description]
[k.debski@samsung.com: make changes accordingly to the mailing list
comments]
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>