staging: wfx: simplify hif_handle_tx_data()

staging: wfx: simplify hif_handle_tx_data()

The last argument of hif_handle_tx_data() was now unused. In add,
hif_handle_tx_data() has nothing to do with HIF layer and should be
renamed. Finally, it not convenient to pass a wfx_vif as parameter. It
is easier to let hif_handle_tx_data() find the interface itself.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200401110405.80282-9-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>