KVM: PPC: Fix typo in rebolting code

When we're loading bolted entries into the SLB again, we're checking if an
entry is in use and only slbmte it when it is.

Unfortunately, the check always goes to the skip label of the first entry,
resulting in an endless loop when it actually gets triggered.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>