vibrator: Fix wrong strength setting

In motion awareness function, it was expected to use
previous sensor data to apply motion or non-motion
strength within 2 secs.
However, it used the default value which is 0 to determine
the strength.

Bug: 153830649
Bug: 153934655
Test: UT and local test
Signed-off-by: chasewu <chasewu@google.com>
Change-Id: Ic12512a9635d95c42bbe52ad92a0ad603af4081b