sound: seq_midi: do not send MIDI reset when closing

Sending a MIDI reset message when closing a port is wrong because we
only want to shut the device up, not to reset all settings.
Furthermore, many devices ignore this message.

Fortunately, the RawMIDI layer already shuts the device up, so we can
ignore this matter here.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>