nightly_revert_checker: fix breakage

We were missing `platforms` here, leading to crashes. Seems best to
default to all platforms getting each revert.

BUG=b:216107005
TEST=Ran the revert checker; no more crashes.

Change-Id: I44658bb01e1c45977ed70c77572cac8a1fd61586
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3429680
Reviewed-by: Jordan Abrahams-Whitehead <ajordanr@google.com>
Commit-Queue: George Burgess <gbiv@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
1 file changed