ipp: use 2 output buffers
ipp: use 2 output buffers

... which avoids hanging if downstream if hangs on to a buffer for a while
(e.g. fakesink) if using pinned buffers.

Downside, however, is increased memory.

Signed-off-by: Mark Nauwelaerts <b7a9d5e0b6d7b100d27ef2a8e80c5c1c14a8de12@collabora.co.uk>

community-ssu/gst-dsp,community-ssu/gst-dsp,community-ssu/gst-dsp