arm64: dts: rockchip: add usb2 nodes to rk3568 device tree

Add the requisite nodes to the rk3568 device tree to enable the usb2
device controllers.
Includes the usb2phy nodes, usb2phy grf nodes, and usb2 controller
nodes.

Signed-off-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Michael Riesch <michael.riesch@wolfvision.net>
Link: https://lore.kernel.org/r/20211215210252.120923-8-pgwipeout@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>