Change touch boost behavior: extent and handles.

This patch does three things:

1. Changes the upmigrate/downmigrate values based on the last boost.
Any touch within 750ms will result in higher upmigrate/downmigrate
values. This is used to approximate detection of constant
input (typing).

2. Moves to multiple handles for handling touch boost rather than
reusing the same handle for each successive component of the boost.

3. Rate limits the boost such that we don't boost more than every 250ms.

bug 24113279
bug 24064601

Change-Id: Ib81e478f17191a1a27e64774e4132fe97e18f124

• power/power.c[diff]
• power/utils.c[diff]