Handle "setup" migration status

Setup status was introduced in 9ca54b9e3a0b753c5b7fad274f98d9de61bf7c4a
in qemu-rdma branch. Not handling it will lead to error

    error: internal error unexpected migration status in setup

and any further attempt to migrate will lead to

    error: internal error unable to execute QEMU command 'migrate': There's a migration process in progress