perf tests record_offcpu.sh: Fix redirection of stderr to stdin

perf tests record_offcpu.sh: Fix redirection of stderr to stdin

[ Upstream commit 9835b742ac3ee16dee361e7ccda8022f99d1cd94 ]

It's not 2&>1, the correct is 2>&1

Fixes: 12240871c3019b73 ("perf offcpu: Update offcpu test for child process")
Signed-off-by: Patrice Duroux <patrice.duroux@gmail.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20230303193058.21274-1-patrice.duroux@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>