wifi: wfx: allow to send frames during ROC

Until now, all the traffic was blocked during scan operation. However,
scan operation is going to be used to implement Remain On Channel (ROC).
In this case, special frames (marked with IEEE80211_TX_CTL_TX_OFFCHAN)
must be sent during the operation.

These frames need to be sent on the virtual interface #2. Until now,
this interface was only used by the device for internal purpose. But
since API 3.9, it can be used to send data during scan operation (we
hijack the scan process to implement ROC).

Thus, we need to change a bit the way we match the frames with the
interface.

Fortunately, the frames received during the scan are marked with the
correct interface number. So there is no change to do on this part.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231004172843.195332-8-jerome.pouiller@silabs.com

wifi: wfx: move wfx_skb_*() out of the header file

There is no real reasons to keep these function in the header file.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231004172843.195332-4-jerome.pouiller@silabs.com

wfx: get out from the staging area

The wfx driver is now mature enough to leave the staging area.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>