staging: wfx: fix status of dropped frames

When wfx_flush() is called, the status of pending frames are reported to
mac80211 with random status. mac80211 probably won't interpret this
status in this case, but it is cleaner to return a correctly initialized
status.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200515083325.378539-8-Jerome.Pouiller@silabs.com


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