staging: vt6655: move setting of PSTxDesc->buff_addr to vnt_tx_packet

Keep setting of this part of the structure with the others.

Only pTDInfo needs carried in the buffer structure.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>