SurfaceTexture: fix up a comment.

    // by calling setBufferCount or setBufferCountServer

    int mBufferCount;

    // mRequestedBufferCount is the number of buffer slots requested by the

    // client. The default is zero, which means the client doesn't care how

    // many buffers there is.

    // mClientBufferCount is the number of buffer slots requested by the client.

    // The default is zero, which means the client doesn't care how many buffers

    // there is.

    int mClientBufferCount;

    // mServerBufferCount buffer count requested by the server-side