Increasing number of framebuffers for MJPEG

Signed-off-by: Carlos Rafael Giani <dv@pseudoterminal.org>
Add available buffer counter workaround for problems with some formats

The VPU wrapper reports consumed frames only for certain formats. For
others, a workaround has to be used. Fortunately, none of these formats
seem to require explicit input<->output frame associations.

Signed-off-by: Carlos Rafael Giani <dv@pseudoterminal.org>