xstart.sh: default to CMT xinput driver
xstart.sh: default to CMT xinput driver

A modification of the previous CMT/syntp switching behavior. It now
defaults to CMT.

BUG=chromium-os:18275
TEST=tested on device

Change-Id: I59324467c8cf07933de9e335e70e4efa5f5bc8d5
Reviewed-on: https://gerrit.chromium.org/gerrit/11689
Reviewed-by: Daniel Kurtz <31914e832df1cd8e5daa417106c0c6f5297b27d7@chromium.org>
Tested-by: Andrew de los Reyes <7bd5f9be8af0e6bb22e5665635eff3a09edb828c@chromium.org>

chadversary/chromiumos.platform.login_manager,chadversary/chromiumos.platform.login_manager,chadversary/chromiumos.platform.login_manager