HO: lchan: store last seen measurement report nr, tweak log

Handover decision 2 will also store the last seen mr nr for neighbor cell
measurements and hence can tell whether a neighbor's measurement is outdated.

Change-Id: Ic1148364597f91b5a55666c80c758b61fa56f582
diff --git a/src/libbsc/chan_alloc.c b/src/libbsc/chan_alloc.c
index 42a9e73..21d5090 100644
--- a/src/libbsc/chan_alloc.c
+++ b/src/libbsc/chan_alloc.c
@@ -414,6 +414,7 @@
 		/* reset measurement report counter and index */
 	        lchan->meas_rep_count = 0;
 	        lchan->meas_rep_idx = 0;
+	        lchan->meas_rep_last_seen_nr = 255;
 
 		/* clear sapis */
 		memset(lchan->sapis, 0, ARRAY_SIZE(lchan->sapis));