cfg80211: clarify set_channel APIs

Now that we've removed all uses of the set_channel
API except for the monitor channel and in libertas,
clarify this. Split the libertas mesh use into a
new libertas_set_mesh_channel() operation, just to
keep backward compatibility, and rename the normal
set_channel() to set_monitor_channel().

Also describe the desired set_monitor_channel()
semantics more clearly.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/libertas/mesh.c b/drivers/net/wireless/libertas/mesh.c
index e87c031..9780775 100644
--- a/drivers/net/wireless/libertas/mesh.c
+++ b/drivers/net/wireless/libertas/mesh.c
@@ -131,16 +131,13 @@
 
 int lbs_mesh_set_channel(struct lbs_private *priv, u8 channel)
 {
+	priv->mesh_channel = channel;
 	return lbs_mesh_config(priv, CMD_ACT_MESH_CONFIG_START, channel);
 }
 
 static uint16_t lbs_mesh_get_channel(struct lbs_private *priv)
 {
-	struct wireless_dev *mesh_wdev = priv->mesh_dev->ieee80211_ptr;
-	if (mesh_wdev->channel)
-		return mesh_wdev->channel->hw_value;
-	else
-		return 1;
+	return priv->mesh_channel ?: 1;
 }
 
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