staging: rtl8723bs: Add missing return for cfg80211_rtw_get_station

With Androidx86 8.1, wificond returns "failed to get
nl80211_sta_info_tx_failed" and wificondControl returns "Invalid signal
poll result from wificond". The fix is to OR sinfo->filled with
BIT_ULL(NL80211_STA_INFO_TX_FAILED).

This missing bit is apparently not needed with NetworkManager, but it
does no harm in that case.

Reported-and-Tested-by: youling257 <youling257@gmail.com>
Cc: linux-wireless@vger.kernel.org
Cc: youling257 <youling257@gmail.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>