handover_test: use 'unknown' BTS type instead of 'sysmobts'

This unit test does not really need a BTS of such specific type.

Change-Id: Id676042518d06e94a9fb20112334280e2b91074b
diff --git a/tests/handover/Makefile.am b/tests/handover/Makefile.am
index 84865a0..fcd171b 100644
--- a/tests/handover/Makefile.am
+++ b/tests/handover/Makefile.am
@@ -59,7 +59,7 @@
 	$(top_builddir)/src/osmo-bsc/bsc_vty.o \
 	$(top_builddir)/src/osmo-bsc/bts_ipaccess_nanobts.o \
 	$(top_builddir)/src/osmo-bsc/bts_ipaccess_nanobts_omlattr.o \
-	$(top_builddir)/src/osmo-bsc/bts_sysmobts.o \
+	$(top_builddir)/src/osmo-bsc/bts_unknown.o \
 	$(top_builddir)/src/osmo-bsc/chan_alloc.o \
 	$(top_builddir)/src/osmo-bsc/codec_pref.o \
 	$(top_builddir)/src/osmo-bsc/gsm_04_08_rr.o \