This is only called in the xhci.c file, so make the symbol static.

Cc: Mathias Nyman <mathias.nyman@intel.com>
Link: https://lore.kernel.org/r/20220901134744.2039891-1-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>