ALSA: seq: virmidi: Fix running status after receiving sysex

The virmidi driver handles sysex event exceptionally in a short-cut
snd_seq_dump_var_event() call, but this missed the reset of the
running status.  As a result, it may lead to an incomplete command
right after the sysex when an event with the same running status was
queued.

Fix it by clearing the running status properly via alling
snd_midi_event_reset_decode() for that code path.

Reported-by: Andreas Steinmetz <ast@domdv.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/3b4a4e0f232b7afbaf0a843f63d0e538e3029bfd.camel@domdv.de
Link: https://lore.kernel.org/r/20200316090506.23966-2-tiwai@suse.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>