softmmu/memory: fix memory_region_ioeventfd_equal()

Eventfd can be registered with a zero length when fast_mmio is true.
Handle this case properly when dispatching through QEMU.

Signed-off-by: Elena Afanasova <eafanasova@gmail.com>
Message-id: cf71a62eb04e61932ff8ffdd02e0b2aab4f495a0.camel@gmail.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
1 file changed