Add a common and microarch JSON, which can be referenced from CPU JSONs.

For now, brief and public description are as event brief event
description from the ARMv8 ARM [0], D7-11.

The list of events is not complete, as not all events will be referenced
yet.

Reference document is at the following:

[0] https://documentation-service.arm.com/static/5fa3bd1eb209f547eebd4141?token=Signed-off-by: John Garry <john.garry@huawei.com>
Acked-by: Will Deacon <will@kernel.org>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Nakamura, Shunsuke/中村 俊介 <nakamura.shun@fujitsu.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxarm@openeuler.org
Link: https://lore.kernel.org/r/1611835236-34696-3-git-send-email-john.garry@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>