perf tools: Add PMU event JSON files for ARM Cortex-A76 and, Neoverse N1.

The source of the event codes and description text was the Neoverse N1
technical reference manual at:

  http://infocenter.arm.com/help/topic/com.arm.doc.100616_0301_01_en/neoverse_n1_trm_100616_0301_01_en.pdf

The Cortex-A76 shares the same event IDs as the Neoverse N1 and they
can be viewed at:

  https://static.docs.arm.com/100798/0400/cortex_a76_trm_100798_0400_00_en.pdf

Signed-off-by: James Clark <james.clark@arm.com>
Cc: "linux-perf-users@vger.kernel.org" <linux-perf-users@vger.kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jeremy Linton <jeremy.linton@arm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: james clark <james.clark@arm.com>
Cc: nd <nd@arm.com>
Link: http://lore.kernel.org/lkml/20190902160713.1425-2-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>