Unlike previous Xbox pads, the Xbox One pad doesn't have "sticky" rumble
packets. The duration is encoded into the command and expiration is handled
by the pad firmware.

ff-memless needs pseudo-sticky behavior for rumble effects to behave
properly for long duration effects. We already specify the maximum rumble
on duration in the command packets, but it's still only good for about 2.5
seconds of rumble. This is easily reproducible running fftest's sine
vibration test.

It turns out there's a repeat count encoded in the rumble command. We can
abuse that to get the pseudo-sticky behavior needed for rumble to behave as
expected for effects with long duration.

By my math, this change should allow a single ff_effect to rumble for 10
minutes straight, which should be more than enough for most needs.
Signed-off-by: Cameron Gutman <aicommander@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>