ALSA: hdspm - Set period_bytes_min to 32 * 4 for new RME cards

On newer RME cards like RayDAT and AIO, the lower bound is 32 samples
per period in contrast to 64 samples as seen on older cards.

We hence lower period_bytes_min to 32 * 4. Four bytes per sample.

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