Exynos: config: Enable hash command

This enables hash command.

Tested with command "hash sha256 0x40008000 0x2B 0x40009000".
Used mm and md to write a standard string to memory location
0x40008000 and ran the above command to verify the output.

Signed-off-by: ARUN MANKUZHI <arun.m@samsung.com>
Signed-off-by: Akshay Saraswat <akshay.s@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>