phy: phy-rockchip-inno-usb2: add rk3568 support

The rk3568 usb2phy is a standalone device with a single muxed interrupt.
Add support for the registers to the usb2phy driver.

Signed-off-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Michael Riesch <michael.riesch@wolfvision.net>
Link: https://lore.kernel.org/r/20211215210252.120923-7-pgwipeout@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>