obmc-console: Consolidate handling of default socket-id

If console-id is not specified on command line or in the config file
then use the default value. ae2460d0b8e8 ("obmc-console: Provide a
default value for `console-id`.") only implemented the default value for
naming the abstract listening socket and overlooked the new DBus path
naming convention.  This caused issues during dbus registration:

```
obmc-console-server: Object name: /xyz/openbmc_project/console/(null)
obmc-console-server: Failed to issue method call: Invalid argument
```

Fixes: ae2460d0b8e8 ("obmc-console: Provide a default value for `console-id`.")
Change-Id: I6d0f7b23cc085992189cd4463129a6aae590b3e7
Signed-off-by: Ninad Palsule <ninadpalsule@us.ibm.com>
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/config.c b/config.c
index 707c024..3d7bd20 100644
--- a/config.c
+++ b/config.c
@@ -332,6 +332,29 @@
 	return 0;
 }
 
+/* Default console id if not specified on command line or in config */
+#define DEFAULT_CONSOLE_ID "default"
+
+/* Get the console id */
+const char *config_resolve_console_id(struct config *config, const char *id_arg)
+{
+	const char *configured;
+
+	if (id_arg) {
+		return id_arg;
+	}
+
+	if ((configured = config_get_value(config, "console-id"))) {
+		return configured;
+	}
+
+	if ((configured = config_get_value(config, "socket-id"))) {
+		return configured;
+	}
+
+	return DEFAULT_CONSOLE_ID;
+}
+
 #ifdef CONFIG_TEST
 int main(void)
 {