Revert "eventpoll: Fix priority inversion problem"

This reverts commit 8c44dac8.

I haven't figured out what the actual bug in this commit is, but I did
spend a lot of time chasing it down and eventually succeeded in
bisecting it down to this.

For some reason, this eventpoll commit ends up causing delays and stuck
user space processes, but it only happens on one of my machines, and
only during early boot or during the flurry of initial activity when
logging in.

I must be triggering some very subtle timing issue, but once I figured
out the behavior pattern that made it reasonably reliable to trigger, it
did bisect right to this, and reverting the commit fixes the problem.

Of course, that was only after I had failed at bisecting it several
times, and had flailed around blaming both the drm people and the
netlink people for the odd problems.  The most obvious of which happened
at the time of the first graphical login (the most common symptom being
that some gnome app aborted due to a 30s timeout, often leading to the
whole session then failing if it was some critical component like
gnome-shell or similar).

Acked-by: Nam Cao <namcao@linutronix.de>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>