tty: pcn_uart: fix memory leak with using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Cc: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20230202141221.2293012-1-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/pch_uart.c

@@ -1775,7 +1775,7 @@ static void pch_uart_exit_port(struct eg20t_port *priv)
 	char name[32];
 
 	snprintf(name, sizeof(name), "uart%d_regs", priv->port.line);
-	debugfs_remove(debugfs_lookup(name, NULL));
+	debugfs_lookup_and_remove(name, NULL);
 	uart_remove_one_port(&pch_uart_driver, &priv->port);
 	free_page((unsigned long)priv->rxbuf.buf);
 }