bpf: pass prog instead of env to bpf_prog_offload_verifier_prep()

Function bpf_prog_offload_verifier_prep(), called from the kernel BPF
verifier to run a driver-specific callback for preparing for the
verification step for offloaded programs, takes a pointer to a struct
bpf_verifier_env object. However, no driver callback needs the whole
structure at this time: the two drivers supporting this, nfp and
netdevsim, only need a pointer to the struct bpf_prog instance held by
env.

Update the callback accordingly, on kernel side and in these two
drivers.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index d665e75..397d206 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -123,15 +123,15 @@ int bpf_prog_offload_init(struct bpf_prog *prog, union bpf_attr *attr)
 	return err;
 }
 
-int bpf_prog_offload_verifier_prep(struct bpf_verifier_env *env)
+int bpf_prog_offload_verifier_prep(struct bpf_prog *prog)
 {
 	struct bpf_prog_offload *offload;
 	int ret = -ENODEV;
 
 	down_read(&bpf_devs_lock);
-	offload = env->prog->aux->offload;
+	offload = prog->aux->offload;
 	if (offload)
-		ret = offload->offdev->ops->prepare(offload->netdev, env);
+		ret = offload->offdev->ops->prepare(offload->netdev, prog);
 	offload->dev_state = !ret;
 	up_read(&bpf_devs_lock);