perf stat: Pass fewer metric arguments

Pass metric_expr and evsel rather than specific variables from the
struct, thereby reducing the number of arguments. This will enable
later fixes.

To reduce the size of the diff, local variables are added to match the
previous parameter names. This isn't done in the case of "name" as
evsel->name is more intention revealing. A whitespace issue is also
addressed.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Kaige Ye <ye@kaige.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: John Garry <john.g.garry@oracle.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240221070754.4163916-1-irogers@google.com