Input: evdev - use keyed wakeups

Some processes, such as systemd, are only polling for EPOLLERR|EPOLLHUP.
As evdev uses unkeyed wakeups, such a poll receives many spurious
wakeups from uninteresting events.

Use keyed wakeups to allow the wakeup target to more efficiently discard
these uninteresting events.

Signed-off-by: Kenny Levinsen <kl@kl.wtf>
Link: https://lore.kernel.org/r/20200410233557.3892-1-kl@kl.wtf


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>