Don't enable virtio for PowerLE

We don't have virtio yet for ppc64le. Switch to scsi-hd for now.

Signed-off-by: Dinar Valeev <dvaleev@suse.com>
Fix type in ppc and s390 personality

uname -n will unlikely return an architrecture.

Should  be uname -m instead

Signed-off-by: Dinar Valeev <dvaleev@suse.com>