Updating the 'v4l-utils' README.chromium to include Revision

Adding Revision field based on 'Version'.

```
$ git remote -v # This redirects to the provided URL.
origin	http://git.linuxtv.org/v4l-utils.git (fetch)
origin	http://git.linuxtv.org/v4l-utils.git (push)

$ git show-ref --tags v4l-utils-1.6.0
02f0dda860a8b7d16792c616bdeb5b02303c288f refs/tags/v4l-utils-1.6.0
```

R=henryhsu@chromium.org, posciak@chromium.org

Bug: chromium:350851535
Change-Id: I096a650dd142f42bd2672fb4d706dce5f9989dbf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5683162
Reviewed-by: Joey Scarr <jsca@google.com>
Reviewed-by: Jordan Brown <rop@google.com>
Auto-Submit: Jordan Brown <rop@google.com>
Commit-Queue: Jordan Brown <rop@google.com>
Cr-Commit-Position: refs/heads/main@{#1382664}