scripts/device-crash-test: Remove fixed isapc-with-iommu entry

Fixed in a0c167a1 ("x86_iommu: check
if machine has PCI bus").

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1521193892-15552-5-git-send-email-thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>