serial: 8250: invert condition to avoid a goto label

Use of "goto" in this code is frowned upon:
 +-------
 |if (port->type == PORT_UNKNOWN)
 |  goto out_unlock;
 |CODE;
 |out_unlock:
 +-------

Instead, simply do:
 +-------
 |if (port->type != PORT_UNKNOWN)
 |  CODE;
 +-------

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250611100319.186924-32-jirislaby@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>