dt-bindings: mmc: rockchip: add rockchip,rk3128-dw-mshc

Add rockchip,rk3128-dw-mshc compatible string.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/f2cb42c8-3664-a2d5-074d-5c9a10c693e8@gmail.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>