staging: vt6656: Fix drivers TBTT timing counter.

The drivers TBTT counter is not synchronized with mac80211 timestamp.

Reorder the functions and use vnt_update_next_tbtt to do the final
synchronize.

Fixes: c151587 ("staging: vt6656: implement TSF counter")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Link: https://lore.kernel.org/r/375d0b25-e8bc-c8f7-9b10-6cc705d486ee@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Malcolm Priestley

drivers/staging/vt6656/main_usb.c

@@ -770,12 +770,15 @@ static void vnt_bss_info_changed(struct ieee80211_hw *hw,
 			vnt_mac_reg_bits_on(priv, MAC_REG_TFTCTL,
 					    TFTCTL_TSFCNTREN);
 
-			vnt_adjust_tsf(priv, conf->beacon_rate->hw_value,
-				       conf->sync_tsf, priv->current_tsf);
-
 			vnt_mac_set_beacon_interval(priv, conf->beacon_int);
 
 			vnt_reset_next_tbtt(priv, conf->beacon_int);
+
+			vnt_adjust_tsf(priv, conf->beacon_rate->hw_value,
+				       conf->sync_tsf, priv->current_tsf);
+
+			vnt_update_next_tbtt(priv,
+					     conf->sync_tsf, conf->beacon_int);
 		} else {
 			vnt_clear_current_tsf(priv);