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.

  This patch is propagated from 3.4 kernel
    commit: 4fcf6f18e4405e202421113241feefa09d91872c
    input: ft5x06_ts: Add debugfs support

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