mmc: Add mmc driver for Sunplus SP7021

This is a patch for mmc driver for Sunplus SP7021 SOC.
Supports eMMC 4.41 DDR 104MB/s speed mode.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tony Huang <tonyhuang.sunplus@gmail.com>
Link: https://lore.kernel.org/r/c92d67596f3cc10d41585b9ab82be7da2cc4c9d8.1669023361.git.tonyhuang.sunplus@gmail.com


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