iwlwifi: make sure reduced tx power bit is valid

Once driver decide to change reduced tx power behavior,
make sure the reduce tx power valid bit is set

Change-Id: I3afae96319292d8cb347a812a948085c5db7ad91
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Reviewed-on: http://git-mwg.jer.intel.com/gerrit/1948
Tested-by: Jenkins
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-agn-lib.c

@@ -643,7 +643,7 @@ static bool iwlagn_fill_txpower_mode(struct iwl_priv *priv,
 		   BT_UART_MSG_FRAME3OBEX_MSK)))) {
 		/* disable reduced tx power */
 		priv->reduced_txpower = false;
-		priv->bt_valid &= ~IWLAGN_BT_VALID_REDUCED_TX_PWR;
+		priv->bt_valid |= IWLAGN_BT_VALID_REDUCED_TX_PWR;
 		need_update = true;
 	}