change GSM48_CMSERV_* to enum type, add names

Prepare handling multiple CM Service Requests in osmo-msc: an enum is more
clear than an int and #defines for passing around and count CM Service types.

Change-Id: I9c2a7adc45ab7a1a7519168e965e7d805e1481ff
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 331c3f0..60ce5d1 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -574,6 +574,7 @@
 
 osmo_rat_type_names;
 osmo_lu_type_names;
+osmo_cm_service_type_names;
 
 local: *;
 };