In commit 6c730e4a we introduced a stub to build the MicroVM
machine without Intel IOMMU. This stub is incomplete for the
other PC machines. Add the missing stubs.

Fixes: 6c730e4a
Reported-by: Travis-CI
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20191220154225.25879-1-philmd@redhat.com>