touch_noise_filter: remove unused function

BUG=chromium:230889
TEST=USE=chrome_internal CFLAGS="-clang -print-cmdline" emerge-x86-alex
     touch_noise_filter passes.

Change-Id: I2420d5456c30f4f6c12ee9a667941095756d1eb0
Reviewed-on: https://gerrit.chromium.org/gerrit/48017
Reviewed-by: Andrew de los Reyes <adlr@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
1 file changed