ALSA: rawmidi: Make tied_device=0 as default / unknown

ALSA: rawmidi: Make tied_device=0 as default / unknown

In the original change, rawmidi_info.tied_device showed -1 for the
unknown or untied device.  But this would require the user-space to
check the protocol version and judge the value conditionally, which
is rather error-prone.

Instead, set the tied_device = 0 to be default as unknown, and
indicate the real device with the offset 1, for achieving more
backward compatibility.

Suggested-by: Jaroslav Kysela <perex@perex.cz>
Link: https://patch.msgid.link/20250114104711.19197-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>