MdeModulePkg/CdExpressPei: Fix capsule size mismatch issue.

MdeModulePkg/CdExpressPei: Fix capsule size mismatch issue.

Current PeiCdExpress driver will return capsule size to
be block aligned.
It will fail if we check the capsuleImageSize field.

The patch correct the returned capsule size.

Tested-by: Eric Dong <eric.dong@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>