Revert "locking/lockdep/selftests: Fix mixed read-write ABBA tests"

This reverts commit d82fed75.

Since we now could handle mixed read-write deadlock detection well, the
self tests could be detected as expected, no need to use this
work-around.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200807074238.1632519-18-boqun.feng@gmail.com