efi: Add EFI file I/O data types

The x86 EFI stub needs to access files, for example when loading
initrd's. Add the required data types.

Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/1318848017-12301-1-git-send-email-matt@console-pimps.org


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>