Revert maximum video codec resolution on Android back to 720p again.

Some low end Android devices still have problems with 1080p support.

BUG=3757
R=niklas.enbom@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/24639004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7228 4adac7df-926f-26a2-2b94-8c16560cd09d