gbproxy_test: Reset the gbproxy before we reset GPRS NS

The peers are (talloc) children of the GPRS NS. This means the
peers (and the rate counters) are currently being deleted twice.

==23446== Invalid write of size 4
==23446==    at 0x403C243: rate_ctr_group_alloc (linuxlist.h:66)
==23446==    by 0x4050974: gprs_nsvc_create (gprs_ns.c:209)
==23446==    by 0x405320D: gprs_ns_instantiate (gprs_ns.c:1330)
==23446==    by 0x804ABEB: main (gbproxy_test.c:666)
==23446==  Address 0x4300694 is 52 bytes inside a block of size 784 free'd
==23446==    at 0x4029DA8: free (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==23446==    by 0x4041B9D: _talloc_free (talloc.c:609)
==23446==    by 0x4043292: talloc_free (talloc.c:578)
==23446==    by 0x40532D3: gprs_ns_destroy (gprs_ns.c:1363)
==23446==    by 0x804ABD7: main (gbproxy_test.c:660)
diff --git a/openbsc/tests/gbproxy/gbproxy_test.c b/openbsc/tests/gbproxy/gbproxy_test.c
index 83832b5..74a220a 100644
--- a/openbsc/tests/gbproxy/gbproxy_test.c
+++ b/openbsc/tests/gbproxy/gbproxy_test.c
@@ -656,9 +656,9 @@
 
 	gbprox_dump_global(stdout, 0);
 
+	gbprox_reset();
 	gprs_ns_destroy(nsi);
 	nsi = NULL;
-	gbprox_reset();
 }
 
 static void test_gbproxy_ident_changes()
@@ -787,9 +787,9 @@
 	gbprox_dump_global(stdout, 0);
 	gbprox_dump_peers(stdout, 0);
 
+	gbprox_reset();
 	gprs_ns_destroy(nsi);
 	nsi = NULL;
-	gbprox_reset();
 }
 
 static void test_gbproxy_ra_patching()
@@ -866,9 +866,9 @@
 	gbprox_dump_global(stdout, 0);
 	gbprox_dump_peers(stdout, 0);
 
+	gbprox_reset();
 	gprs_ns_destroy(nsi);
 	nsi = NULL;
-	gbprox_reset();
 }