staging: vt6655: mac8021 conversion: add new tx functions

vnt_fill_txkey a mac80211 repacement for s_vFillTxKey

vnt_generate_fifo_header mac80211 replacement for vGenerateFIFOHeader

vnt_beacon_make for making and despatching beacon.

vnt_beacon_enable to enabling beacon

struct vnt_tx_fifo_head is also added to replace typedef
struct tagSTxBufHead that will be removed later.

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