input: support for Cypress TMG i2c capacitive touchscreen

Based on a driver from HTC.
 - lots of cleanups.
 - don't do averaging/snapping for x/y coordinates
   add a fuzz value instead, and report the raw events to userspace.

Signed-off-by: Dima Zavin <dima@android.com>
[sboyd: drop Kconfig entry, include/linux file]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>