iwlwifi: mvm: remove useless WARN_ON and rely on cfg80211's combination

We advertise one STATION vif only, so this just can't
happen. Remove this useless WARN_ON.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/power.c

@@ -613,8 +613,6 @@ static void iwl_mvm_power_get_vifs_iterator(void *_data, u8 *mac,
 		break;
 
 	case NL80211_IFTYPE_STATION:
-		/* only a single MAC of the same type */
-		WARN_ON(power_iterator->bss_vif);
 		power_iterator->bss_vif = vif;
 		if (mvmvif->phy_ctxt)
 			if (mvmvif->phy_ctxt->id < MAX_PHYS)