net: fix build error in devmap helper calls

Initial patches missed case with CONFIG_BPF_SYSCALL not set.

Fixes: 11393cc9 ("xdp: Add batching support to redirect map")
Fixes: 97f91a7c ("bpf: add bpf_redirect_map helper routine")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>