phy: phy-rockchip-inno-usb2: add phy description for px30

The px30 soc from Rockchip shares the same register description as
the rk3328, so can re-use its definitions.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>