Input: atmel_mxt_ts - implement debug output for messages

Add a debug switch which causes all messages from the touch controller to be
dumped to the dmesg log with a set prefix "MXT MSG:". This is used by Atmel
user-space utilities to debug touch operation. Enabling this output does
impact touch performance.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - add memory access interface via sysfs

Atmel maXTouch chips can be addressed via an "Object Based Protocol" which
defines how i2c registers are mapped to different functions within the
chips. This interface exposes the register map and allows user-space
utilities to inspect and alter object configuration, and to view diagnostic
data, while the device is running.

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Acked-by: Benson Leung <bleung@chromium.org>
Input: atmel_mxt_ts - implement improved debug message interface

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
Input: atmel_mxt_ts - fix return code bug in mem_access_write

Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>