input: ft5x06: create secure touch sysfs files

This patch creates two sysfs files for secure touch -
secure_touch and secure_touch_enable which will be
accessed by secure ui app. We also define the store
and show function for these sysfs files.

Change-Id: I4bc156de12a8b41c3640c4f1fb2d32ca3d8b5b43
Signed-off-by: Abinaya P <abinayap@codeaurora.org>