src: use namespace prefix osmo_counter*

Summary of changes:

s/struct counter/struct osmo_counter/g
s/counter_inc/osmo_counter_inc/g
s/counter_get/osmo_counter_get/g
s/counter_reset/osmo_counter_reset/g
s/counter_alloc/osmo_counter_alloc/g
s/counter_free/osmo_counter_free
diff --git a/openbsc/src/libmsc/db.c b/openbsc/src/libmsc/db.c
index f08fb79..d25bc21 100644
--- a/openbsc/src/libmsc/db.c
+++ b/openbsc/src/libmsc/db.c
@@ -1242,7 +1242,7 @@
 	return 0;
 }
 
-int db_store_counter(struct counter *ctr)
+int db_store_counter(struct osmo_counter *ctr)
 {
 	dbi_result result;
 	char *q_name;