perf timechart: Remove redundant variable assignment

This patch makes a minor change that removes a redundant variable
assignment. The assignment before the for loop is duplicated by the
initialization within the loop header.

Signed-off-by: Luo Yifan <luoyifan@cmss.chinamobile.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241111095209.276332-1-luoyifan@cmss.chinamobile.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: Luo Yifan

tools/perf/builtin-timechart.c

@@ -1158,7 +1158,6 @@ static void draw_io_bars(struct timechart *tchart)
 			}
 
 			svg_box(Y, c->start_time, c->end_time, "process3");
-			sample = c->io_samples;
 			for (sample = c->io_samples; sample; sample = sample->next) {
 				double h = (double)sample->bytes / c->max_bytes;