When using KVM, using a specific cpu type will only work if the
host CPU really is that exact CPU type.

During testing we can simply use the 'max' CPU which will select
all the features available from the host.

This allow running this test on a Cavium CN8890 (ThunderX cores).

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210205144345.2068758-4-f4bug@amsat.org>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>