cpus: initialize cpu->memory_dispatch This fixes a NULL pointer dereference in s390x-softmmu. On pretty much all other architectures, creating an MMIO region calls cpu_reload_memory_map. On s390, however, there are no MMIO regions and everything is done via hypercalls. Fixes: 9d82b5a792236db31a75b9db5c93af69ac07c7c5 Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>