ALSA: pcm_dmaengine: Use pcm_for_each_format() macro for PCM format iteration

ALSA: pcm_dmaengine: Use pcm_for_each_format() macro for PCM format iteration

The new macro can fix the sparse warnings gracefully:
  sound/core/pcm_dmaengine.c:429:50: warning: restricted snd_pcm_format_t degrades to integer
  sound/core/pcm_dmaengine.c:429:55: warning: restricted snd_pcm_format_t degrades to integer
  sound/core/pcm_dmaengine.c:429:79: warning: restricted snd_pcm_format_t degrades to integer

No functional changes, just sparse warning fixes.

Link: https://lore.kernel.org/r/20200206163945.6797-8-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>