arm64: dts: juno: Use proper DT node name for USB

The EHCI/OCHI DT binding requires to use "usb" as the node name stub.

Replace the existing name with "usb" to comply with the binding.

Link: https://lore.kernel.org/r/20200513103016.130417-13-andre.przywara@arm.com


Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>