Remove the error return on SetAGC failure introduced by r3605.
Remove the error return on SetAGC failure introduced by r3605.

BUG=webrtc:1464

Review URL: https://webrtc-codereview.appspot.com/1166005

git-svn-id: 917f5d3ca488f358c4d40eaec14422cf392ccec9@3616 4adac7df-926f-26a2-2b94-8c16560cd09d

TimothyGu/libilbc,mwgoldsmith/ilbc,ShiftMediaProject/libilbc,mwgoldsmith/ilbc,ShiftMediaProject/libilbc,mwgoldsmith/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,mwgoldsmith/libilbc,mwgoldsmith/libilbc,mwgoldsmith/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,mwgoldsmith/ilbc,mwgoldsmith/ilbc,TimothyGu/libilbc