MdeModulePkg/SdMmcPciHcDxe: Update comment for spec compliance status

MdeModulePkg/SdMmcPciHcDxe: Update comment for spec compliance status

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1441

This commit will update the file-level comments within the SdMmcPciHcDxe
to reflect the latest specification compliance status of the driver.

Cc: Ray Ni <ray.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>