Based on a patch from Andrew Eikum <aeikum@codeweavers.com>.

Dark Souls Remasters checks for xinput devices when it receives a
WM_DEVICECHANGE message. We would only poll for new devices if it had
been at least 2 seconds since the last check. So often, DS would receive
the message, but we would refuse to poll for devices, so the game would
think no controller was present.

This commit fixes that by also subscribing to event notifications and
triggering a poll.
Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>