input: touchscreen: Add an interface to expose TP features to userspace

 * Needs to implement and register ops from TP driver
 * Access them via /sys/touchpanel/*
 * Export capacitive keys status

Change-Id: I2baa61c6055ca6f6207ac0d6f627fe03048ccfb6
Signed-off-by: danascape <saalimquadri1@gmail.com>
Signed-off-by: danascape <danascape@gmail.com>