Limit touch sampling rate for falsing.

Our falsing manager has a hard time with high sample rates. It's tuned
for a predefined rate of 60hz. In this CL, we simply drop extra
samples since they can cause false positives in our falsing.

Bug: 130256776
Test: Manual

Change-Id: I5d4dc239e4185f984f108b92e352e5184c52821a