arm64: dts: imx8mm-evk: Move port under USB connector

Per nxp,ptn5110.yaml, 'port' should be placed under 'connector'.

Do as requested to fix the following dt-schema warning:

imx8mm-evkb.dtb: tcpc@50: 'port' does not match any of the regexes: 'pinctrl-[0-9]+'
	from schema $id: http://devicetree.org/schemas/usb/nxp,ptn5110.yaml#



Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>