Add umc page retirement for umc v12_0.

V2:
  1. Changed umc page retirement check condition
     to call umc_v12_0_is_uncorrectable_error.
  2. Use memset to clear the contents of the umc
     error address structure.
Signed-off-by: YiPeng Chai <YiPeng.Chai@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>