venc: use less buffers for HD codecs
venc: use less buffers for HD codecs

No need to have so many, and the buffer drops improve quite a lot.

Signed-off-by: Felipe Contreras <de77a8b9cd239b204c19c52ed62e48ab47243362@nokia.com>

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