iwlwifi: introduce iwl_advanced_bt_coexist()

We use priv->cfg->bt_params && priv->cfg->bt_params->advanced_bt_coexist
conditional in few places, merge it into one function.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-power.c b/drivers/net/wireless/iwlwifi/iwl-power.c
index 1eec18d..25f7d47 100644
--- a/drivers/net/wireless/iwlwifi/iwl-power.c
+++ b/drivers/net/wireless/iwlwifi/iwl-power.c
@@ -226,8 +226,7 @@
 	else
 		cmd->flags &= ~IWL_POWER_SHADOW_REG_ENA;
 
-	if (priv->cfg->bt_params &&
-	    priv->cfg->bt_params->advanced_bt_coexist) {
+	if (iwl_advanced_bt_coexist(priv)) {
 		if (!priv->cfg->bt_params->bt_sco_disable)
 			cmd->flags |= IWL_POWER_BT_SCO_ENA;
 		else
@@ -313,8 +312,7 @@
 	else
 		cmd->flags &= ~IWL_POWER_SHADOW_REG_ENA;
 
-	if (priv->cfg->bt_params &&
-	    priv->cfg->bt_params->advanced_bt_coexist) {
+	if (iwl_advanced_bt_coexist(priv)) {
 		if (!priv->cfg->bt_params->bt_sco_disable)
 			cmd->flags |= IWL_POWER_BT_SCO_ENA;
 		else