Uninitialized struct scroll which is used to pass state between
scrollstrip ISR and button_read_device() can bomb out whole
button subsytem.
Change-Id: I3b415c22cfee4181b2132cddaeff68797c7cc0ea
Scrollstrip (as well as scrollwheel on ipods/sansas) works like
quadrature encoder. The states of input lines are tracked by the
gpio ISR and when the sequence is correct, appropriate button
event is pushed to the button queue directly. The downside of
this implementation is that scrollstrip doesn't emit _REL
events which has some weird consequences. For the scrollwheels
some hack have been crafted in action system to accomodate for
this. I don't like this approach. IMO the correct fix is to
properly emit _REL event when the user stops interacting with
the device or reverses the direction of the move. This patch
implements timeout which forces to emit _REL when expired.
Change-Id: I588ac5810dd2ab00c68935d23a62979cb1c2a912
