perf bench messaging: Fix coding style issues for sched-messaging

Fixed several code style issues in sched-messaging:
1. Use one space around "-" and "+" operators.
2. When a long line is broken, the operator is at the end of the line.

Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20230923093037.961232-2-yangjihong1@huawei.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>