stats: add site_id scope to ipa-rsl tcp stat names

Multiple IPA units can have the same bts_id but scoping by their
site_ids will make them unique. This also clarifies the "bts"
number being communicated. It is not the bts configuration index
in osmo-bsc.cfg, it is the bts id specified in the vty line:

bts X
 ipa unit-id SITE BTS

Change-Id: I3b44319fb4bc6a812800001c58dfe1a664645b43
diff --git a/src/input/ipaccess.c b/src/input/ipaccess.c
index 8dc1008..9659b36 100644
--- a/src/input/ipaccess.c
+++ b/src/input/ipaccess.c
@@ -296,7 +296,7 @@
 			struct e1inp_ts *ts;
 			struct osmo_fd *newbfd;
 			struct e1inp_line *new_line;
-			char tcp_stat_name[32];
+			char tcp_stat_name[64];
 
 			sign_link =
 				line->ops->sign_link_up(&unit_data, line,
@@ -343,8 +343,8 @@
 				     "could not register FD\n");
 				goto err;
 			}
-			snprintf(tcp_stat_name, sizeof(tcp_stat_name), "bts.%u.ipa-rsl.%u",
-				unit_data.bts_id, unit_data.trx_id);
+			snprintf(tcp_stat_name, sizeof(tcp_stat_name), "site.%u.bts.%u.ipa-rsl.%u",
+				unit_data.site_id, unit_data.bts_id, unit_data.trx_id);
 			osmo_stats_tcp_osmo_fd_register(newbfd, tcp_stat_name);
 
 			e1i_ts = ipaccess_line_ts(newbfd, new_line);