cfg80211: allow per interface TX power setting

The TX power setting is currently per wiphy (hardware
device) but with multi-channel capabilities that doesn't
make much sense any more.

Allow drivers (and mac80211) to advertise support for
per-interface TX power configuration. When the TX power
is configured for the wiphy, the wdev will be NULL and
the driver can still handle that, but when a wdev is
given the TX power can be set only for that wdev now.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/wext-compat.c b/net/wireless/wext-compat.c
index 6488d2d..742ab6e 100644
--- a/net/wireless/wext-compat.c
+++ b/net/wireless/wext-compat.c
@@ -895,7 +895,7 @@
 		return 0;
 	}
 
-	return rdev_set_tx_power(rdev, type, DBM_TO_MBM(dbm));
+	return rdev_set_tx_power(rdev, wdev, type, DBM_TO_MBM(dbm));
 }
 
 static int cfg80211_wext_giwtxpower(struct net_device *dev,
@@ -914,7 +914,7 @@
 	if (!rdev->ops->get_tx_power)
 		return -EOPNOTSUPP;
 
-	err = rdev_get_tx_power(rdev, &val);
+	err = rdev_get_tx_power(rdev, wdev, &val);
 	if (err)
 		return err;