Input: psmouse - rearrange Focaltech init code

The fact that we were calling focaltech_init() even when Focaltech support
is disabled was confusing. Rearrange the code so that if support is
disabled we continue to fall through the rest of protocol probing code
until we get to full reset that Focaltech devices need to work properly.

Also, replace focaltech_init() with a stub now that it is only called when
protocol is enabled.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Tested-by: Marcin Sochacki <msochacki+kernel@gmail.com>
Tested-by: Till <till2.schaefer@uni-dortmund.de>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>