kvm: we never have overlapping slots in kvm_set_phys_mem()

kvm: we never have overlapping slots in kvm_set_phys_mem()

The way flatview handles memory sections, we will never have overlapping
memory sections in kvm.

address_space_update_topology_pass() will make sure that we will only
get called for

a) an existing memory section for which we only update parameters
(log_start, log_stop).
b) an existing memory section we want to delete (region_del)
c) a brand new memory section we want to add (region_add)

We cannot have overlapping memory sections in kvm as we will first remove
the overlapping sections and then add the ones without conflicts.

Therefore we can remove the complexity for handling prefix and suffix
slots.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20170911174933.20789-5-david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>