perf jevents: Add new structure to pass json fields.

This patch adds new structure called 'json_event' inside jevents.c
file to improve the callback prototype inside jevent files.

Initially, whenever user want to add new field, they need to update
in all function callback which make it more and more complex with
increased number of parmeters.

With this change, we just need to add it in new structure 'json_event'.

Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Link: http://lore.kernel.org/lkml/20200907064133.75090-3-kjain@linux.ibm.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>