Fixed wrong #define when compiling on ARM with non-NEON selection.

This CL fixes a (likely) typo/copy-paste issue when compiling on ARM
with NEON disabled.

R=andrew@webrtc.org, rtoy@google.com

Review URL: https://webrtc-codereview.appspot.com/38939004

git-svn-id: http://webrtc.googlecode.com/svn/deps/third_party/openmax@8304 4adac7df-926f-26a2-2b94-8c16560cd09d