mac80211: fix ipw200 build with kernel < 4.10

The __change_mtu() function is only compiled when
CPTCFG_IPW2200_PROMISCUOUS is set, more it to the general area.

Signed-off-by: Hauke Mehrtens <[email protected]>

package/kernel/mac80211/patches/build/015-ipw200-mtu.patch

@@ -0,0 +1,34 @@
+--- a/drivers/net/wireless/intel/ipw2x00/ipw2200.c
++++ b/drivers/net/wireless/intel/ipw2x00/ipw2200.c
+@@ -11498,6 +11498,15 @@ static const struct attribute_group ipw_
+ 	.attrs = ipw_sysfs_entries,
+ };
+ 
++#if LINUX_VERSION_IS_LESS(4,10,0)
++static int __change_mtu(struct net_device *ndev, int new_mtu){
++	if (new_mtu < 68 || new_mtu > LIBIPW_DATA_LEN)
++		return -EINVAL;
++	ndev->mtu = new_mtu;
++	return 0;
++}
++#endif
++
+ #ifdef CPTCFG_IPW2200_PROMISCUOUS
+ static int ipw_prom_open(struct net_device *dev)
+ {
+@@ -11546,15 +11555,6 @@ static netdev_tx_t ipw_prom_hard_start_x
+ 	return NETDEV_TX_OK;
+ }
+ 
+-#if LINUX_VERSION_IS_LESS(4,10,0)
+-static int __change_mtu(struct net_device *ndev, int new_mtu){
+-	if (new_mtu < 68 || new_mtu > LIBIPW_DATA_LEN)
+-		return -EINVAL;
+-	ndev->mtu = new_mtu;
+-	return 0;
+-}
+-#endif
+-
+ static const struct net_device_ops ipw_prom_netdev_ops = {
+ #if LINUX_VERSION_IS_LESS(4,10,0)
+ 	.ndo_change_mtu = __change_mtu,