efi_loader: fix depends on line of EFI_LOADER

This line is shown as

   depends on (ARM64 ||\302\240ARM) && OF_LIBFDT

on my Emacs.  Use ASCII characters only.

Assuming it is (ARM64 || ARM), remove the redundancy.
Unlike Linux, CONFIG_ARM includes CONFIG_ARM64 in U-Boot.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Alexander Graf <agraf@suse.de>