fixed compilation of chan_misdn, #11269, thanks IgorG.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89319 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_misdn.c

@@ -1686,11 +1686,11 @@ static char *complete_ch_helper(struct ast_cli_args *a, int rpos)
 			if (++which > a->n)
 				break;
 		}
-		ast_mutex_unlock(&c->lock);
+		ast_channel_unlock(c);
 	}
 	if (c) {
 		ret = ast_strdup(c->name);
-		ast_mutex_unlock(&c->lock);
+		ast_channel_unlock(c);
 	} else
 		ret = NULL;
 	return ret;