[Chromecast] Fix IsSupportedVideoConfig() on Android.

Since Android does not explicitly list all supported levels, we
should check whether the level is smaller or equal to supported
levels.

BUG=Internal b/34175462 b/34808220 b/35257976
TEST=base_unittests, media_unittests, cast_media_unittests

Review-Url: https://codereview.chromium.org/2697033003
Cr-Commit-Position: refs/heads/master@{#450979}
2 files changed