hw/arm/virt: Enable MTE via a machine property

Control this cpu feature via a machine property, much as we do
with secure=on, since both require specialized support in the
machine setup to be functional.

Default MTE to off, since this feature implies extra overhead.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200713213341.590275-2-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

include/hw/arm/virt.h

@@ -140,6 +140,7 @@ typedef struct {
     bool its;
     bool virt;
     bool ras;
+    bool mte;
     OnOffAuto acpi;
     VirtGICType gic_version;
     VirtIOMMUType iommu;