Input: tsc2005 - remove 'disable' sysfs attribute

I believe that enable/disable functionality should not be implemented on
the individual driver level but rather in device core, potentially
reusing parts of PM framework. Therefore the driver-specific "disable"
attribute is removed from the mainline driver.

Tested-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>