arm64: zynqmp: Update USB node handle from dwc3 to usb

The DWC3 bindings require all USB node handles to be '^usb@[0-9a-f]+$'.
Update the same in ZynqMP device tree.

Signed-off-by: Manish Narani <manish.narani@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/26fc2777eeb92cb5cb1d558d7c19cfb54ac42d0c.1642160613.git.michal.simek@xilinx.com