chromeos-base/ec-utils: Only build usb_updater

There is now a second usb_updater2 in the same folder, which we do
not want to build (at least for now).

BUG=chromium:725152
TEST=emerge-soraka -aC flashmap
     cros_workon-soraka start ec-utils
     emerge-soraka -av --nodeps ec-utils

Change-Id: I64aae765891ae8502dd48280a21ec8d0d1ba0173
Reviewed-on: https://chromium-review.googlesource.com/511522
Commit-Ready: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
1 file changed