arm: dts: k3-am654: remove usb0

The pinmux for usb0 is missing from the Linux board dtb file. Remove it
until we can introduce it in Linux

Tested-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Bryan Brattlof <bb@ti.com>
Reviewed-by: Nishanth Menon <nm@ti.com>