ALSA: hdspm - Use snd_ctl_enum_info() in snd_hdspm_info_autosync_ref

Also use snd_ctl_enum_info() to fill the autosync text fields on AES32
and MADI cards (only users of snd_hdspm_info_autosync_ref).

Signed-off-by: Adrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>