Add function to check MS GEA capabilities

Add function which parses MS network capability IE value for bits
indicating support for particular version of GEA.

Change-Id: I785cef37dd272a2fab9b172f6e1392f865174e9a
Relates: OS#1582
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index ebeabcd..96f615e 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -44,6 +44,7 @@
 gprs_cipher_key_length;
 gprs_tlli_type;
 gprs_tmsi2tlli;
+gprs_ms_net_cap_gea_supported;
 
 gsm48_gmm_cause_names;
 gsm48_gsm_cause_names;