HID: alps: fix multitouch cursor issue

Issue reproduction procedure:

1. three or more fingers put on Touchpad.
2. release fingers from Touchpad.
3. move the cursor by one finger.
4. the cursor does not move.

Cause:

We do not notify multi fingers state correctly to input subsystem.  For
example, when three fingers release from Touchpad, fingers state is 3 -> 0. It
needs to notify first, second and third finger's releasing state.

Fix this by not breaking out on z axis and move x,y,z input handling
code to the correct place so that it's in fact per-finger.

[jkosina@suse.cz: reword changelog]
Signed-off-by: Masaki Ota <masaki.ota@jp.alps.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>