Rename POWER DHCP filenames to elf
grubppc64le.efi are not good names for the files as these binaries are NOT EFI on IBM POWER platform. We need to rename them to *.elf files and pass the correct DHCP filename option for those architectures.
This is not important, IBM POWER provisioning should work, the filenames just need to be named with the weird "efi" extension.
Also Grub2 templates must be changed, "linuxefi" must be replaced with "linux" as described in https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Installation_Guide/chap-installation-server-setup.html#sect-network-boot-setup-ppc-grub2