Migrating a VM during reboot sometimes results in differences
between the source and destination in the SMRAM area.

This is because migration_bitmap_sync() only fetches from KVM
the dirty log of address_space_memory.  SMRAM memory slots
are ignored and the modifications to SMRAM are not sent to the
destination.

Reported-by: He Rongguang <herongguang.he@huawei.com>
Reviewed-by: He Rongguang <herongguang.he@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>