rpb.inc: allow FFmpeg to be included in RPB builds
rpb.inc: allow FFmpeg to be included in RPB builds

Signed-off-by: Zoltan Kuscsik <9b42050009adc334da08769081a7fe47b373edeb@gmail.com>

fboudra/meta-rpb,96boards/meta-rpb,fboudra/meta-rpb,96boards/meta-rpb,fboudra/meta-rpb