MdeModulePkg: Return invalid param in LocateProtocol for Protocol==NULL

MdeModulePkg: Return invalid param in LocateProtocol for Protocol==NULL

Return EFI_INVALID_PARAMETER in LocateProtocol for Protocol==NULL to
follow UEFI 2.7 spec

PiSmmCore is also updated as the EFI_SMM_SYSTEM_TABLE2.SmmLocateProtocol
is reusing the definition of EFI_LOCATE_PROTOCOL.

Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>