The evdev multitouch protocol requires that a last MT sync event must be
sent after all touches are up. This change adds the last MT sync event
to the hid-magicmouse driver.

Also, don't send events when a touch leaves.
Signed-off-by: NChase Douglas <chase.douglas@canonical.com>
Acked-by: NMichael Poole <mdpoole@troilus.org>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>