ALSA: seq: Introduce SNDRV_SEQ_IOCTL_USER_PVERSION ioctl

ALSA: seq: Introduce SNDRV_SEQ_IOCTL_USER_PVERSION ioctl

For the future extension of ALSA sequencer ABI, introduce a new ioctl
SNDRV_SEQ_IOCTL_USER_PVERSION.  This is similar like the ioctls used
in PCM and other interfaces, for an application to specify its
supporting ABI version.

The use of this ioctl will be mandatory for the upcoming UMP support.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230523075358.9672-25-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>