ASoC: rockchip: pdm: Add support for rk3568 pdm

This patch adds compatible for rk3568 which is the same
with rv1126.

Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Link: https://lore.kernel.org/r/1630675410-3354-3-git-send-email-sugar.zhang@rock-chips.com


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