This reverts commit 441892f6197efbe014cfb54fc6f9d43ed7e425bb.

The two 32-bit UEFI systems I've tried booting on only support the fallback UEFI
path, that's not an option for us with 32-bit syslinux UEFI, as explained in the
commit we're presently reverting.

I also tried, and failed, to convince GRUB2 installed in the fallback location
(EFI/BOOT/bootia32.efi) to chainload into 32-bit syslinux UEFI.

So I'm giving up with using syslinux for 32-bit UEFI.

Refs: #8471