intel/batch_decoder: Recurse for all 2nd level batches

intel/batch_decoder: Recurse for all 2nd level batches

Our attempt to restart the loop with the second level batch worked at
one point but got broken at some point.  It was too fragile anyway and
we're not likely to have enough secondaries to actually overflow the
stack so we may as well recurse in both cases.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>