MdeModulePkg/UniversalPayload: Add definition for extra info in payload

MdeModulePkg/UniversalPayload: Add definition for extra info in payload

The payload is in ELF format per the universal payload spec.
UNIVERSAL_PAYLOAD_INFO_HEADER is stored in the ELF payload as a separate
section named ".upld_info".

Extra data needed by payload is stored in sections whose name starts
with ".upld.".

Signed-off-by: Ray Ni <ray.ni@intel.com>
Cc: Maurice Ma <maurice.ma@intel.com>
Cc: Guo Dong <guo.dong@intel.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>