xen: arm: enable perf counters

xen: arm: enable perf counters

As well as the existing common perf counters add a bunch of ARM
specifics, including the various trap types, vuart/vgic/vtimer
accesses and different types of interrupt.

Adjust the common code so that the columns line up again, not sure
when/where this went wrong.

This is mostly the set of stuff I happened to be interested in, it can
be made more (or less) fine grained as the need arises.

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