USB: xhci: Check URB's actual transfer buffer size.

Make sure that the amount of data the xHC says was transmitted is less
than or equal to the size of the requested transfer buffer.  Before, if
the host controller erroneously reported that the number of bytes
untransferred was bigger than the buffer in the URB, urb->actual_length
could be set to a very large size.

Make sure urb->actual_length <= urb->transfer_buffer_length.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>