xhci: handle failed buffer copy to URB sg list and fix a W=1 copiler warning

Set the urb->actual_length to bytes successfully copied in case all bytes
weren't copied from a temporary buffer to the URB sg list.
Also print a debug message

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20210617150354.1512157-4-mathias.nyman@linux.intel.com


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