dev-install: drop devmode check

The new C++ wrapper checks this for us.

BUG=chromium:935142
TEST=precq passes

Change-Id: I727db8d57f1194dcc71d13cd176be227f402db83
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/1789857
Reviewed-by: Alex Klein <saklein@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
1 file changed