free surface buffers before trying to allocate new ones, so we have more chance of success

{

    Mutex::Autolock _l(mLock);

    surface_info_t* info = mInfo;

    mBuffer.clear(); // free buffer before allocating a new one

    sp<Buffer> buffer = new Buffer(mWidth, mHeight, mFormat, mFlags);

    status_t err = buffer->initCheck();

    if (LIKELY(err == NO_ERROR)) {