mmc: sdhci-of-dwcmshc: add support for rk3588

Add support for RK3588's DWCMSHC controller, which is used for
providing the rootfs on the RK3588 evaluation board.

Signed-off-by: Yifeng Zhao <yifeng.zhao@rock-chips.com>
[port from vendor BSP]
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20220504213251.264819-12-sebastian.reichel@collabora.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>