kvm: clear dirty bitmaps from all overlapping memslots

kvm: clear dirty bitmaps from all overlapping memslots

Currently MemoryRegionSection has 1:1 mapping to KVMSlot.
However next patch will allow splitting MemoryRegionSection into
several KVMSlot-s, make sure that kvm_physical_log_slot_clear()
is able to handle such 1:N mapping.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <20190924144751.24149-3-imammedo@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>