touchpad: multitap state transitions use the same timing used for taps

Multitap sequences (more than 2 taps) had a 180ms timer set only on press,
not on release.
New taps within those 180ms could either trigger multitap+drag or another
multitap (for N+1 taps), resetting the timer on press once again.
If no new tap appears within those 180ms, the sequence was considered
complete.

This behavior differed from regular taps: for the very first tap of a
sequence the timer was set both on touch and on release.

The multitap timing caused misdetection of triple-tap-and-drag sequences as
the timer was hit frequently. Some of those were correctly detected, others
as tripletap only.

Changing the timer to be set on press **and** release gives us a more lenient
timeout. 180ms for tap-and-drag and 180ms for the next tap down after
release. This was also the behavior for the xorg synaptics driver.

Note that quadruple-tap-and-drag didn't suffer from this because the timeout
resulted in double-tap + double-tap-and-drag. Which has the same
user-visible effect.