Add new log category 'ms'

This is useful to track the lifecycle of MS objects. The RLCMAC cateogry
used so far in those log messages is too broad.

Change-Id: Ib4ce88d0f7309ac77c064a94bb0d667e8dbc33dd
diff --git a/tests/ms/MsTest.cpp b/tests/ms/MsTest.cpp
index 7b7d59a..2a15a7b 100644
--- a/tests/ms/MsTest.cpp
+++ b/tests/ms/MsTest.cpp
@@ -542,7 +542,7 @@
 	log_set_log_level(osmo_stderr_target, LOGL_INFO);
 	log_set_print_category(osmo_stderr_target, 0);
 	log_set_print_category_hex(osmo_stderr_target, 0);
-	log_parse_category_mask(osmo_stderr_target, "DPCU,3:DRLCMAC,3");
+	log_parse_category_mask(osmo_stderr_target, "DPCU,3:DRLCMAC,3:DMS,3");
 
 	the_pcu = gprs_pcu_alloc(tall_pcu_ctx);