selftests/timers: Add missing fflush(stdout) calls

selftests/timers: Add missing fflush(stdout) calls

BugLink: https://bugs.launchpad.net/bugs/1838824
[ Upstream commit fe48319243a626c860fd666ca032daacc2ba84a5 ]

When running under a pipe, some timer tests would not report output in
real-time because stdout flushes were missing after printf()s that lacked
a newline. This adds them to restore real-time status output that humans
can enjoy.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>