drivers:usb:common:fsl-dt-fixup: fix return value of fdt_usb_get_node_type

Changes the return type of fdt_usb_get_node_type from char* to int

Signed-off-by: Sriram Dash <sriram.dash@nxp.com>
Signed-off-by: Rajesh Bhagat <rajesh.bhagat@nxp.com>