freetdm: fixing RDNIS-Screen value mis-displaying string in decimal format

libs/freetdm/mod_freetdm/mod_freetdm.c

@@ -1715,7 +1715,7 @@ ftdm_status_t ftdm_channel_from_event(ftdm_sigmsg_t *sigmsg, switch_core_session
 
 		var_value = ftdm_sigmsg_get_var(sigmsg, "ss7_rdnis_screen_ind");
 		if (!ftdm_strlen_zero(var_value)) {
-			switch_channel_set_variable_printf(channel, "sip_h_X-FreeTDM-RDNIS-Screen", "%d", var_value);
+			switch_channel_set_variable_printf(channel, "sip_h_X-FreeTDM-RDNIS-Screen", "%s", var_value);
 		}
 
 		var_value = ftdm_sigmsg_get_var(sigmsg, "ss7_rdnis_pres_ind");