DWMMC: Initialise dwmci and resolve EMMC read write issues

This patch enumerates dwmci and set auto stop command during
dwmci initialisation.
EMMC read/write is not happening in current implementation
due to improper fifo size computation. Hence modified the fifo size
computation to resolve EMMC read write issues.

Signed-off-by: Amar <amarendra.xt@samsung.com>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>