get rid of grub suggestion

We ask the probing agent for the loader type. Unfortunately this still
returns grub on x86. I sugggest to skip this step altogether. We decide the
loader type in yast2-bootloader anyway. If we want to enable it on openSUSE
we should do it in this function somewhere.

Not sure where grub2 on ppc64le comes from, though...
release 3.1.37
Merge pull request #90 from yast/bnc_no_grub

Bnc no grub