volume_snapshot_list: remove $ip parameter

We want to handle ssh connections somewhere else (not inside the
storage plugins).

PVE/Storage/ZFSPlugin.pm

@@ -363,7 +363,7 @@ sub volume_has_feature {
 }
 
 sub volume_snapshot_list {
-    my ($class, $scfg, $storeid, $volname, $prefix, $ip) = @_;
+    my ($class, $scfg, $storeid, $volname, $prefix) = @_;
     # return an empty array if dataset does not exist.
     die "Volume_snapshot_list is not implemented for ZFS over iSCSI.\n";
 }