Revert "[media] rc: ir-rc6-decoder: Add encode capability"

This reverts commit cf257e28.

The current code is not mature enough, the API should allow a single
protocol to be specified. Also, the current code contains heuristics
that will depend on module load order.

Signed-off-by: David Härdeman <david@hardeman.nu>
Acked-by: Antti Seppälä <a.seppala@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>