perf vendor events arm64: Enable JSON events for ThunderX2 B0

There is MIDR change on ThunderX2 B0, adding an entry to mapfile to
enable JSON events for B0.

Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ganapatrao Kulkarni <gpkulkarni@gklkml16.com>
Cc: Jayachandran C <jnair@caviumnetworks.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <robert.richter@cavium.com>
Cc: William Cohen <wcohen@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20180307110803.32418-1-ganapatrao.kulkarni@cavium.com
[ Fixup wrt recent patchset by John Garry ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>