nfp: bpf: drop support for cls_bpf with legacy actions

Only support BPF_PROG_TYPE_SCHED_CLS programs in direct
action mode.  This simplifies preparing the offload since
there will now be only one mode of operation for that type
of program.  We need to know the attachment mode type of
cls_bpf programs, because exit codes are interpreted
differently for legacy vs DA mode.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>