selftests: harness: avoid false negatives if test has no ASSERTs

selftests: harness: avoid false negatives if test has no ASSERTs

BugLink: https://bugs.launchpad.net/bugs/1959376
[ Upstream commit 3abedf4646fdc0036fcb8ebbc3b600667167fafe ]

Test can fail either immediately when ASSERT() failed or at the
end if one or more EXPECT() was not met. The exact return code
is decided based on the number of successful ASSERT()s.

If test has no ASSERT()s, however, the return code will be 0,
as if the test did not fail. Start counting ASSERT()s from 1.

Fixes: 369130b63178 ("selftests: Enhance kselftest_harness.h to print which assert failed")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>