lib/flashrom: clean up do_cmd

Nothing using the pipe arguments anymore, clean that up.

BUG=chromium:990438
TEST="mosys memory spd print all" on grunt

Change-Id: I18b5acf0d0c33793f9c5bb370bd9df3f72fb3337
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/mosys/+/2489799
Tested-by: Jack Rosenthal <jrosenth@chromium.org>
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>
Commit-Queue: Jack Rosenthal <jrosenth@chromium.org>
1 file changed