This comment was added by commit 6cd425be2b (Allow update rt_period_us
and rt_runtime_us, Nov 4 2016), and the test case was added by commit
51baedf3f3 (Add integration for update rt period and runtime,
Nov 28 2016), making the comment obsolete.
Remove it.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>