A BLS configuration is the default and in this case the installkernel-bls
script is used. For a non-BLS configuration the grubby-deprecated package
installs an installkernel that uses the new-kernel-pkg script.
So there is no need to check for GRUB_ENABLE_BLSCFG=true. Also, this check
is wrong for s390x and was causing the installkernel-bls script to no call
kernel-install on this platform.
Resolves: rhbz#1647721
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>