Initial import: sweep2wake
s2w: Register power key input device

-sweep2wake resumes from sleep my simulating a power key press.
It needs the power key input device to do this and in the case
of Venturi; it's s3c-keypad defined in mach-venturi.c
s2w: adjust tuneables for venturi

-These were obviously for a much higher resolution device. Tone them
down for venturi.
s2w: cytma340 - plug in the touchscreen.

-hooking the sweep detection method for sweep2wake and clear some
vars for it at appropriate times.

-NOTE: As of this commit, and as a consequence of keeping the touchscreen
driver awake, simply pressing the capacitive buttons will wake the
device as well on USA variant. Not sure about INT...
s2w: add to venturi defconfig