Change vld and vst to specify only elements and size not sign for better arm compiler compatability.
BUG=none
TEST=none
R=kma@webrtc.org, mflodman@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/1643004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@721 16f28f9a-4ce2-e073-06de-1de4eb20be90