Currently the grubby script re-generates a GRUB config file that contains
menuentry commands for every /boot/loader/entries/*.conf file snippet.
But this is only needed for ppc64le machines that have a Petitboot version
that doesn't support parsing BLS snippets. Instead of generating a config
on any ppc64le machine, restrict this for the case where is really needed.
The /etc/grub.d/10_linux script already takes this into account and does
not add menuentry commands unless is needed. But the grubby script didn't
check this, causing changing kernel cmdline params to not work on ppc64le.
Resolves: rhbz#1896222
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>