[SGSN] SNDCP: Fix off-by-one error missing last segment in defrag

When we defragment the segments from the defrage queue, we have
to iterate all the way up to (and including) the last segment number
that we have received.

openbsc/src/gprs/gprs_sndcp.c

@@ -150,7 +150,7 @@ static int defrag_segments(struct gprs_sndcp_entity *sne)
 
 	npdu = msg->data;
 
-	for (seg_nr = 0; seg_nr < sne->defrag.highest_seg; seg_nr++) {
+	for (seg_nr = 0; seg_nr <= sne->defrag.highest_seg; seg_nr++) {
 		struct defrag_queue_entry *dqe;
 		uint8_t *data;