Extend the write_tx_data callback with a txdesc parameter to allow
access to the tx desciptor while preparing the tx data.
Signed-off-by: NHelmut Schaa <helmut.schaa@googlemail.com>
Acked-by: NGertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>