ALSA: core: use ARRAY_SIZE() in snd_minor_info_read()

Use ARRAY_SIZE(snd_minors) instead of SNDRV_OS_MINORS directly, for
consistency with snd_find_free_minor() and snd_unregister_device() in
the same file. No functional change.

Signed-off-by: bui duc phuc <phucduc.bui@gmail.com>
Link: https://patch.msgid.link/20260707074556.569451-1-phucduc.bui@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>