cros_bundle_firmware: drop --force-rw option

It was only effective if fmap.dts pre-configured the firmware to choose
the read-only path, which only a small number of ancient boards did.

BUG=none
TEST=none
CQ-DEPEND=CL:371179

Change-Id: I67e7a6cdfb712bfb29cfff0545081d7d0113def6
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://chromium-review.googlesource.com/371280
Commit-Ready: Patrick Georgi <pgeorgi@chromium.org>
Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
2 files changed