Add I2C related definition in PI 1.3 spec.

Signed-off-by: Elvin Li <elvin.li@intel.com>
Reviewed-by: Leahy Leroy P <leroy.p.leahy@intel.com>


git-svn-id: svn://svn.code.sf.net/p/edk2/code/trunk/edk2/MdePkg@14548 6f19259b-4bc3-4df7-8a09-765794883524