usb: fsl: Renaming fdt_fixup_erratum and fdt_fixup_usb_erratum

The functions fdt_fixup_erratum and fdt_fixup_usb_erratum are
fsl/nxp specific. So, make them explicit by renaming them
fsl_fdt_fixup_erratum and fsl_fdt_fixup_usb_erratum

Signed-off-by: Sriram Dash <sriram.dash@nxp.com>