Follow UEFI2.4.a spec, add more description on parameter check.

Signed-off by: jiewen yao <jiewen.yao@intel.com>
Reviewed by: qin long <qin.long@intel.com>

git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/MdePkg@15127 6f19259b-4bc3-4df7-8a09-765794883524