Fix wrong usage sizeof(SIZE).

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Sergey Isakov <isakov-sl@bk.ru>
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Sergey Isakov <isakov-sl@bk.ru>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Ruiyu Ni<ruiyu.ni@intel.com>

git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/OptionRomPkg@15672 6f19259b-4bc3-4df7-8a09-765794883524