xen: arm: Do not expose PMU to domain 0

xen: arm: Do not expose PMU to domain 0

It uses a PPI which we cannot route to a guest, and will surely need
more support than just that anyway.

I noticed this on Mustang with UEFI where the built in DTB contains a
node of this type.

According to linux/Documentation/devicetree/bindings/arm/pmu.txt the
ARM v7 (Cortex-A{7,15}) PMUs require a PPI too, so blacklist them as
well.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Julien Grall <julien.grall@citrix.com>