ALSA: cmi8330: Use managed buffer allocation

Clean up the driver with the new managed buffer allocation API.
The actual removal of superfluous code will be done in ad1848 and sb
codec drivers later.

Link: https://lore.kernel.org/r/20191209094943.14984-12-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>