ALSA: hdspm - Use snd_ctl_enum_info for most text arrays

Use snd_ctl_enum_info() to fill most of the enumerated controls. More
non-trivial occurrences will follow in separate commits.

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