usb: xhci: Remove unused function

Now that we replaced the xhci_create_usb3_bos_desc() function. We can
remove it along with the static usb_bos_descriptor structure.

Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/ce0acbbd0bd3c3c3a08e6418ab3bdb431a44bbfd.1615432770.git.Thinh.Nguyen@synopsys.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>