Variable names are inconsistent in hists__for_each macro().

Due to this inconsistency, the macro replaces its second argument with
"fmt" regardless of its original name.

So far it works because only "fmt" is passed to the second argument.
However, this behavior is not expected and should be fixed.

Fixes: f0786af5 ("perf hists: Introduce hists__for_each_format macro")
Fixes: aa6f50af ("perf hists: Introduce hists__for_each_sort_list macro")
Signed-off-by: Yuya Fujita <fujita.yuya@fujitsu.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/OSAPR01MB1588E1C47AC22043175DE1B2E8520@OSAPR01MB1588.jpnprd01.prod.outlook.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>