input: move touchpoint counting up

The touchpoint counting is needed regardless of what we do with the
touch events, so move it out of process_touch_normal() into the caller
notify_touch_normalized().

This is pure refactoring.

Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
v1 Tested-by: Matt Hoosier <matt.hoosier@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>