[legal] Add missing FILE_LICENCE declarations

Add missing FILE_LICENCE declarations to EFI headers based on the
corresponding source file.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/efi/efi_file.h

  *
  */
 
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
 extern int efi_file_install ( EFI_HANDLE handle );
 extern void efi_file_uninstall ( EFI_HANDLE handle );
 

src/include/ipxe/efi/efi_snp.h

  *
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #include <ipxe/list.h>
 #include <ipxe/netdevice.h>
 #include <ipxe/efi/efi.h>