netdevsim: Don't accept device bound programs

Commit 2b3486bc2d23 ("bpf: Introduce device-bound XDP programs") introduced
device-bound programs by largely reusing existing offloading infrastructure.
This changed the semantics of 'prog->aux->offload' a bit. Now, it's non-NULL
for both offloaded and device-bound programs.

Instead of looking at 'prog->aux->offload' let's call bpf_prog_is_offloaded
which should be true iff the program is offloaded and not merely device-bound.

Fixes: 2b3486bc2d23 ("bpf: Introduce device-bound XDP programs")
Reported-by: [e-mail]
Signed-off-by: Stanislav Fomichev <[e-mail]>
Signed-off-by: Daniel Borkmann <[e-mail]>
Reviewed-by: Jakub Kicinski <[e-mail]>
Cc: Dipendra Khadka <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

drivers/net/netdevsim/bpf.c

···
 {
 	struct nsim_bpf_bound_prog *state;
 
-	if (!prog || !prog->aux->offload)
+	if (!prog || !bpf_prog_is_offloaded(prog->aux))
 		return;
 
 	state = prog->aux->offload->dev_priv;
···
 	if (!bpf->prog)
 		return 0;
 
-	if (!bpf->prog->aux->offload) {
+	if (!bpf_prog_is_offloaded(bpf->prog->aux)) {
 		NSIM_EA(bpf->extack, "xdpoffload of non-bound program");
 		return -EINVAL;
 	}