iwlwifi: mvm: fix antenna selection when BT is active

When BT is active, we want to avoid the shared antenna for
management frame to make sure we don't disturb BT. There
was a bug in that code because it chose the antenna
BIT(ANT_A) where ANT_A is already a bitmap (0x1). This
means that the antenna chosen in the end was ANT_B.
While this is not optimal on devices with 2 antennas (it'd
disturb BT), it is critical on single antenna devices like
3160 which couldn't connect at all when BT was active.

This fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=97181

CC: <stable@vger.kernel.org> [3.17+]
Fixes: 34c8b24ff2 ("iwlwifi: mvm: BT Coex - avoid the shared antenna for management frames")
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/mvm/tx.c

@@ -252,7 +252,7 @@ void iwl_mvm_set_tx_cmd_rate(struct iwl_mvm *mvm, struct iwl_tx_cmd *tx_cmd,
 
 	if (info->band == IEEE80211_BAND_2GHZ &&
 	    !iwl_mvm_bt_coex_is_shared_ant_avail(mvm))
-		rate_flags = BIT(mvm->cfg->non_shared_ant) << RATE_MCS_ANT_POS;
+		rate_flags = mvm->cfg->non_shared_ant << RATE_MCS_ANT_POS;
 	else
 		rate_flags =
 			BIT(mvm->mgmt_last_antenna_idx) << RATE_MCS_ANT_POS;