net: usb: hso: use swap macro in hso_kick_transmit

Make use of the swap macro and remove unnecessary variable *temp*.
This makes the code easier to read and maintain. Also, slightly
refactor some code due to the removal of *temp*.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>