ASoC: dma-sh7760: Use managed buffer allocation

Clean up the drivers with the new managed buffer allocation API.
The superfluous snd_pcm_lib_malloc_pages() and
snd_pcm_lib_free_pages() calls are dropped.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20191210142614.19405-7-tiwai@suse.de


Signed-off-by: Mark Brown <broonie@kernel.org>