phy: add inno-usb2-phy driver for hi3798cv200 SoC

It adds inno-usb2-phy driver for hi3798cv200 SoC USB 2.0 support.  One
inno-usb2-phy device can support up to two PHY ports.  While there is
device level reference clock and power reset to be controlled, each PHY
port has its own utmi reset that needs to assert/de-assert as needed.

Hi3798cv200 needs to access PHY port0 register via particular peripheral
syscon controller register to control PHY, like turning on PHY clock.

Signed-off-by: Pengcheng Li <lpc.li@hisilicon.com>
Signed-off-by: Jiancheng Xue <xuejiancheng@hisilicon.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>