input: ft5x06_ts: Add debugfs support

Add debugfs support to provide addr and data
entries to read registers from controller.
Writing into the registers is not supported
as it might corrupt controller. Also add suspend
entry to dynamically test suspend and resume.

Change-Id: If61bbbefdbf624f62b07c2a96d28c8338bd948c1
Signed-off-by: Mohan Pallaka <mpallaka@codeaurora.org>