tty-ask-password-agent: Do tell what directory we failed to open

(cherry picked from commit 267b3e41df)

src/tty-ask-password-agent/tty-ask-password-agent.c

@@ -501,7 +501,7 @@ static int show_passwords(void) {
                 if (errno == ENOENT)
                         return 0;
 
-                log_error("opendir(): %m");
+                log_error("opendir(/run/systemd/ask-password): %m");
                 return -errno;
         }