ASoC: rockchip: i2s: Improve dma data transfer efficiency

This patch changes dma data burst from 4 to 8 to improve
data transfer efficiency.

Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Link: https://lore.kernel.org/r/1629950520-14190-3-git-send-email-sugar.zhang@rock-chips.com


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