arm64: dts: imx8mn: update usb compatible

Update usb compatible per binding doc

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20230322052504.2629429-5-peng.fan@oss.nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>