MdePkg/UefiBaseType.h: treat EBC as a non-native machine type

MdePkg/UefiBaseType.h: treat EBC as a non-native machine type

Instead of classifying EBC as a supported machine type and have special
handling in DXE core for loading EBC images, make it a foreign type and
rely on the EDK2 PE/COFF image emulator protocol to claim the image when
the DXE core finds that it cannot be supported natively.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Hao Wu <hao.a.wu@intel.com>