phy: amlogic: Add Amlogic A1 USB2 PHY Driver

This adds support for the USB2 PHY found in the Amlogic A1 SoC Family.

It supports host mode only.

Signed-off-by: Yue Wang <yue.wang@amlogic.com>
Signed-off-by: Hanjie Lin <hanjie.lin@amlogic.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>