kex: aliased avp_printf to pv_printf

- backward compatibility reasons
- reported by Santiago Gimeno
(cherry picked from commit 0408f81197da38a9ab94c46698d3db10e01b39c1)

modules_k/kex/kex_mod.c

@@ -76,6 +76,8 @@ static cmd_export_t cmds[]={
 			0, ANY_ROUTE },
 	{"pv_printf", (cmd_function)w_pv_printf,    2, pv_printf_fixup,
 			0, ANY_ROUTE },
+	{"avp_printf", (cmd_function)w_pv_printf,   2, pv_printf_fixup,
+			0, ANY_ROUTE },
 
 	{0,0,0,0,0,0}
 };