usb: cdns3: add NXP imx8qm glue layer

There is a Cadence USB3 core for imx8qm and imx8qxp SoCs, the cdns
core is the child for this glue layer device.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>