input: touchscreen: clean ITE tech TS driver

Clean ITE tech touchscreen driver.
Structurize driver data members, replace standard logging
function calls & messages, change to proper function names,
change to proper variable names, remove unnecessary sysfs entry.

Change-Id: I02bcea18e93146b68aaeb8d81fa7bec67b5bcc73
Signed-off-by: Shantanu Jain <shjain@codeaurora.org>