arm64: dtsi: imx8mp: add usb nodes

imx8mp integrates 2 identical dwc3 based USB3 controllers and
Synopsys phys, each instance has additional wakeup logic to
support low power mode, so the glue layer need a node with dwc3
core sub node.

Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Li Jun <jun.li@nxp.com>
Link: https://lore.kernel.org/r/1609241866-9508-4-git-send-email-jun.li@nxp.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>