staging: wfx: improve interface between data_tx.c and queue.c

staging: wfx: improve interface between data_tx.c and queue.c

Currently, wfx_pending_remove() (from queue.c) call wfx_skb_dtor()
(from data_tx.c) that forward the tx status to mac80211.

Moreover, there no purpose to retrieve a frame from the pending queue
without dequeuing it. So, the main purpose of wfx_pending_remove() is to
forward the tx status to mac80211.

Let's make the architecture cleaner:
  - merge wfx_pending_remove() into wfx_pending_get()
  - call wfx_skb_dtor() from data_tx.c

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200401110405.80282-27-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>