v4l2_stateful_decoder: s/buffer/mmap/ for command line option

This CL proposes renaming the --buffer command line option to
--mmap to better reflect what it does.

This change should not add new functionality.

BUG=b:194942425
TEST=emerge+deploy on hana then
tast run <IP> video.PlaformDecoding.v4l2* on hana
with the CL https://crrev.com/c/3257849.

Change-Id: Ieef6bbc9c70602a02f6599a9f96a34fb25561c9a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/drm-tests/+/3258234
Tested-by: Miguel Casas <mcasas@chromium.org>
Reviewed-by: Nathan Hebert <nhebert@chromium.org>
Reviewed-by: Steve Cho <stevecho@chromium.org>
Commit-Queue: Miguel Casas <mcasas@google.com>
1 file changed