TouchWake implementation v1.2 (Yank555.lu)

- Finger and Pen working
- Call detection working through proxy detection
- use of wakelock is optional (sysfs switchable)

Issues left to resolve :

- Finger detection only works after screen is off for 1-2 seconds

 * SysFs interface :
 *
 * /sys/class/misc/touchwake/enabled (rw) : 1 - on / 0 - off
 *
 *     Enable / Disable TouchWake (default = disabled)
 *
 *     NB: Turning the device off with the power key will disable touchwake
 *
 * /sys/class/misc/touchwake/delay (rw) :
 *
 *     Sets the delay in ms to keep touchscreen / pen actively listening for touch after screen goes off
 *
 *     NB: A value of 0 equals "infinite", will drain battery !
 *
 * /sys/class/misc/touchwake/proximity_threshold (rw) :
 *
 *     Sets the threshold from which to consider the proxy triggered (which will disable touchwake)
 *
 *     NB: This serves as a kind of in-call detection to not turn the screen on during a call when placing
 *         the device to the ear
 *
 * /sys/class/misc/touchwake/use_wakelock (rw) : 1 - on / 0 - off
 *
 *     Enable / Disable using a wakelock to keep device awake while TouchWake is active (default = enabled)
 *
 * /sys/class/misc/touchwake/version (ro) :
 *
 *     Display the current version of the eXtended ConTRoLs
 *
 * /sys/class/misc/touchwake/debug (ro) :
 *
 *     Display debugging info (only if debugging is active at compilation time)