iotests: Fix 083

iotests: Fix 083

As of 8f9e835fd2e687d2bfe936819c3494af4343614d, probing should be
disabled in the qemu-iotests (at least when using qemu-io). This broke
083's reference output (which consisted mostly of "Could not read image
for determining its format").

This patch fixes it.

Note that one case which failed before is now successful: Disconnect
after data. This is due to qemu having read twice before (once for
probing, once for the qemu-io read command), but only once now (the
qemu-io read command). Therefore, reading is successful (which is
correct).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>