memory: remove assertion on memory_region_destroy Now that memory_region_destroy can be called from an RCU callback, checking the BQL-protected global memory_region_transaction_depth does not make much sense. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>