input: touchscreen: refactoring dt2w code

Refactoring the dt2w code by applying mainline code
style guidelines. Although this changes a lot by
moving some stuff into the header it should have no
actual functional change.
The very only change i did is using power efficient
workqueues instead of the cpu-bound one to prevent
battery drain a bit.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>

michael1900: Fixed some cherry-picking errors caused
by my previous "dt2w: from early to powersuspend" commit
and reenabled dt2w by default.

Conflicts:
	drivers/input/touchscreen/doubletap2wake.c
	drivers/input/touchscreen/sweep2wake.c