ALSA: virtio: build PCM devices and substream hardware descriptors

ALSA: virtio: build PCM devices and substream hardware descriptors

Like the HDA specification, the virtio sound device specification links
PCM substreams, jacks and PCM channel maps into functional groups. For
each discovered group, a PCM device is created, the number of which
coincides with the group number.

Introduce the module parameters for setting the hardware buffer
parameters:
  pcm_buffer_ms [=160]
  pcm_periods_min [=2]
  pcm_periods_max [=16]
  pcm_period_ms_min [=10]
  pcm_period_ms_max [=80]

Signed-off-by: Anton Yakovlev <anton.yakovlev@opensynergy.com>
Link: https://lore.kernel.org/r/20210302164709.3142702-5-anton.yakovlev@opensynergy.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>