MdePkg: Update the comments of HiiConfigAccess ExtractConfig

Add the status code return for HiiConfigAccess ExtractConfig to
align with UEFI spec 2.10.

REF: UEFI spec 2.10 section 35.5.2

Signed-off-by: Suqiang Ren <suqiangx.ren@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>