Remove __inline from WebRtcIsacfix_Log2Q8.

This function is used externally and needs to always be emitted, also
there's no point in explicitly marking this as inline.

R=tina.legrand@webrtc.org
BUG=

Review URL: https://webrtc-codereview.appspot.com/13279004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6926 4adac7df-926f-26a2-2b94-8c16560cd09d