bpf: Remove unnecessary checks on the offset of btf_field.

reg_find_field_offset() always return a btf_field with a matching offset
value. Checking the offset of the returned btf_field is unnecessary.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240523174202.461236-2-thinker.li@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/bpf/verifier.c

@@ -11640,7 +11640,7 @@ __process_kf_arg_ptr_to_graph_node(struct bpf_verifier_env *env,
 
 	node_off = reg->off + reg->var_off.value;
 	field = reg_find_field_offset(reg, node_off, node_field_type);
-	if (!field || field->offset != node_off) {
+	if (!field) {
 		verbose(env, "%s not found at offset=%u\n", node_type_name, node_off);
 		return -EINVAL;
 	}