This commit adds support to piton_mmc driver for OpenPiton-riscv64
This driver has many things set as preconfigured because the hardware
automatically configures most of the settings during startup.
Signed-off-by: Tianrui Wei <tianrui-wei@outlook.com>
Signed-off-by: Jonathan Balkind <jbalkind@ucsb.edu>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
