b43: N-PHY: don't calculate values for TSSI if we can't transmit

This process requires sending some sample tone, so make sure we're
allowed to transmit first.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/phy_n.c

@@ -3957,7 +3957,8 @@ static void b43_nphy_tx_power_ctl_idle_tssi(struct b43_wldev *dev)
 	u32 tmp;
 	s32 rssi[4] = { };
 
-	/* TODO: check if we can transmit */
+	if (phy->chandef->chan->flags & IEEE80211_CHAN_NO_IR)
+		return;
 
 	if (b43_nphy_ipa(dev))
 		b43_nphy_ipa_internal_tssi_setup(dev);