Add mask & shift definition of MAM_D(0~3)MEM for all mmhub
ranges.

Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>