The vbios mistakenly sets this bit on some boards without ECC.
This can lead to reduced performance in some workloads.  Disable
the bit if the board does not have ECC.
Reviewed-by: NHawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: NJunwei Zhang <Jerry.Zhang@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>