touchpad: Put state unrolling code in a tp_clear_state() helper function

touchpad: Put state unrolling code in a tp_clear_state() helper function

For touchpads with top softbuttons we don't want to fully disable the touchpad
on suspend, as we want to keep the top softbuttons working for the trackpoint.

So in the suspended state some of the touchpad sub-statemachines will keep
running (e.g. buttons) where others (e.g. tap) will not. This means that
we will need to clear the touchpad state on resume too, to avoid things
being in an inconsistent state after resume.

This commit factors out the state clearing code into a helper functions, so
that the same code can be used on resume.

No functional changes.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>