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/verifier.c b/kernel/bpf/verifier.c
index 75dab40..8d09779 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6368,7 +6368,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
 		goto skip_full_check;
 
 	if (bpf_prog_is_dev_bound(env->prog->aux)) {
-		ret = bpf_prog_offload_verifier_prep(env);
+		ret = bpf_prog_offload_verifier_prep(env->prog);
 		if (ret)
 			goto skip_full_check;
 	}