carl9170: Only specify interface combinations if more than one interface is possible

Otherwise carl9170 triggers a warning in cfg80211, from net/wireless/core.c

	/* Combinations with just one interface aren't real */
	if (WARN_ON(c->max_interfaces < 2))

Note: The number of supported interfaces is set by
the carl9170 firmware. The default number of
supported interfaces for all current firmwares is 2.
Therefore this warning can only be observed with
custom firmwares.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/carl9170/fw.c

@@ -215,6 +215,24 @@ static int carl9170_fw_tx_sequence(struct ar9170 *ar)
 	return 0;
 }
 
+static void carl9170_fw_set_if_combinations(struct ar9170 *ar,
+					    u16 if_comb_types)
+{
+	if (ar->fw.vif_num < 2)
+		return;
+
+	ar->if_comb_limits[0].max = ar->fw.vif_num;
+	ar->if_comb_limits[0].types = if_comb_types;
+
+	ar->if_combs[0].num_different_channels = 1;
+	ar->if_combs[0].max_interfaces = ar->fw.vif_num;
+	ar->if_combs[0].limits = ar->if_comb_limits;
+	ar->if_combs[0].n_limits = ARRAY_SIZE(ar->if_comb_limits);
+
+	ar->hw->wiphy->iface_combinations = ar->if_combs;
+	ar->hw->wiphy->n_iface_combinations = ARRAY_SIZE(ar->if_combs);
+}
+
 static int carl9170_fw(struct ar9170 *ar, const __u8 *data, size_t len)
 {
 	const struct carl9170fw_otus_desc *otus_desc;
@@ -341,16 +359,7 @@ static int carl9170_fw(struct ar9170 *ar, const __u8 *data, size_t len)
 		}
 	}
 
-	ar->if_comb_limits[0].max = ar->fw.vif_num;
-	ar->if_comb_limits[0].types = if_comb_types;
-
-	ar->if_combs[0].num_different_channels = 1;
-	ar->if_combs[0].max_interfaces = ar->fw.vif_num;
-	ar->if_combs[0].limits = ar->if_comb_limits;
-	ar->if_combs[0].n_limits = ARRAY_SIZE(ar->if_comb_limits);
-
-	ar->hw->wiphy->iface_combinations = ar->if_combs;
-	ar->hw->wiphy->n_iface_combinations = ARRAY_SIZE(ar->if_combs);
+	carl9170_fw_set_if_combinations(ar, if_comb_types);
 
 	ar->hw->wiphy->interface_modes |= if_comb_types;