flashrom_tester: adopt `clap` for command line parsing

The ad-hoc parsing we had is cumbersome to extend and it's relatively
easy to import a library to do it for us. Plus we get improved help
output for "free."

BUG=b:140262368
TEST=Exercised command line manually on a device
BRANCH=None

Change-Id: I3c499bcfabdc26cfe0ac15a09da2cb1c517138f8
Signed-off-by: Peter Marheine <pmarheine@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/flashrom/+/1789333
Reviewed-by: Sam McNally <sammc@chromium.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
2 files changed