ALSA: hdspm - DRY cleanup of snd_pcm_ops

This commit removes code duplication between
snd_hdspm_{capture,playback}_ops. No semantic changes intended, this is
purely cosmetic.

Signed-off-by: Adrian Knoth <aknoth@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>