sccp_user: fix local_ssn_avail if called with PC in tuple format

caught by dialyzer
diff --git a/src/sccp_user.erl b/src/sccp_user.erl
index 0df5c7d..b1f9445 100644
--- a/src/sccp_user.erl
+++ b/src/sccp_user.erl
@@ -102,7 +102,7 @@
 	end;
 local_ssn_avail(Ssn, Pc) when is_integer(Ssn), is_tuple(Pc) ->
 	PcInt = osmo_util:pointcode2int(Pc),
-	local_ssn_avail(Ssn, Pc).
+	local_ssn_avail(Ssn, PcInt).
 
 
 dump() ->