osmo-hnbgw: vty: revamp output of context maps on 'show hnb'

Instead of listing each and every context map, rather output a summary of
context counts.

Rationale: in a list of a hundred HNBs, I don't want to also see a dozen (or
potentially thousands of) context map lines for each. Furthermore, the conn IDs
aren't necessarily useful on network traces either.

For example, what was shown as SUA Id is incidentally the SCCP Reference, but
this is not a hard requirement and may change. Also, the reference is shown in
wireshark as a hex in mismatching byte order ... so rather don't bother.

The result now looks like

  OsmoHNBGW> show hnb all
  HNB (r=192.168.0.124:29169<->l=192.168.0.9:29169) "000295-0000152614@ap.ipaccess.com"
      MCC 901 MNC 70 LAC 14357 RAC 11 SAC 1 CID 8595638 SCCP-stream:HNBAP=0,RUA=0
      IuCS: 1 contexts: inactive-reserved:1
      IuPS: 1 contexts: active:1
  1 HNB connected

Related: OS#2772 OS#2773
Change-Id: Iae76b68e85863c8663bb5c508b85534c00e1d2c9
diff --git a/include/osmocom/iuh/context_map.h b/include/osmocom/iuh/context_map.h
index 8d957d6..6279b91 100644
--- a/include/osmocom/iuh/context_map.h
+++ b/include/osmocom/iuh/context_map.h
@@ -8,8 +8,13 @@
 	MAP_S_ACTIVE,		/* currently active map */
 	MAP_S_RESERVED1,	/* just disconnected, still resrved */
 	MAP_S_RESERVED2,	/* still reserved */
+	MAP_S_NUM_STATES	/* Number of states, keep this at the end */
 };
 
+extern const struct value_string hnbgw_context_map_state_names[];
+static inline const char *hnbgw_context_map_state_name(enum hnbgw_context_map_state val)
+{ return get_value_string(hnbgw_context_map_state_names, val); }
+
 struct hnb_context;
 struct hnbgw_cnlink;