Input: tca8418 - use the interrupt trigger from the device tree

commit 259b77ef853cc375a5c9198cf81f9b79fc19413c upstream.

The TCA8418 might be used using different interrupt triggers on various
boards. This is not working so far because the current code forces a
falling edge trigger.

The device tree already provides a trigger type, so let's use whatever it
sets up, and since we can be loaded without DT, keep the old behaviour for
the non-DT case.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Oliver Neukum <ONeukum@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>