staging: wfx: drop useless structs only used in hif_req_tx

The structs hif_queue, hif_data_flags, hif_tx_flags and
hif_ht_tx_parameters have no real reasons to exist. Drop them and
simplify access to fields of struct hif_req_tx.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200907101521.66082-20-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>