MAINTAINERS: Add James and Mike as Arm64 performance events reviewers

James, Mike and Leo have been doing all the reviews and development work
for the Coresight perf tools for a couple of years now.  As such remove
my name and add James and Mike as official reviewers (Leo is already
listed as such).

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: James Clark <james.clark@arm.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>