vty: cleanup logging functions

* remove unused parameter from logging_vty_add_cmds()
* mark log level descriptors static
* change internal static function int check_log_to_target() to more
  appropriate bool should_log_to_target()
* deprecate log_vty_command_*() from public API as it should only be
  used by logging_vty_add_cmds()

Change-Id: I0e9ddd7ba3ce211302d99a3494eb408907a2916e
Related: OS#71
diff --git a/include/osmocom/core/logging.h b/include/osmocom/core/logging.h
index 41a5d77..77343e9 100644
--- a/include/osmocom/core/logging.h
+++ b/include/osmocom/core/logging.h
@@ -332,8 +332,8 @@
 void log_del_target(struct log_target *target);
 
 /* Generate command string for VTY use */
-const char *log_vty_command_string(const struct log_info *info);
-const char *log_vty_command_description(const struct log_info *info);
+const char *log_vty_command_string() OSMO_DEPRECATED("For internal use inside libosmocore only.");
+const char *log_vty_command_description() OSMO_DEPRECATED("For internal use inside libosmocore only.");
 
 struct log_target *log_target_find(int type, const char *fname);
 extern struct llist_head osmo_log_target_list;
diff --git a/include/osmocom/vty/logging.h b/include/osmocom/vty/logging.h
index 9e4b98f..544d117 100644
--- a/include/osmocom/vty/logging.h
+++ b/include/osmocom/vty/logging.h
@@ -4,6 +4,6 @@
 #define FILTER_STR	"Filter log messages\n"
 
 struct log_info;
-void logging_vty_add_cmds(const struct log_info *cat);
+void logging_vty_add_cmds();
 struct vty;
 struct log_target *osmo_log_vty2tgt(struct vty *vty);