Input: alps - use the generic process_bitmap function for v5 touchpads

Now that the generic process_bitmap function has been improved to offer
accurate coordinates for the first touch we can use it for v5 (dolphin)
touchpads too.

Besides being a nice code cleanup this also fixes the saw tooth pattern
in the coordinates for the second touch the dolphin specific version had.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>