bpf: Check the validity of max_rdwr_access for sock local storage map iterator

The value of sock local storage map is writable in map iterator, so check
max_rdwr_access instead of max_rdonly_access.

Fixes: 5ce6e77c7edf ("bpf: Implement bpf iterator for sock local storage map")
Signed-off-by: Hou Tao <[e-mail]>
Acked-by: Yonghong Song <[e-mail]>
Acked-by: Martin KaFai Lau <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

net/core/bpf_sk_storage.c

···
 	if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
 		goto put_map;
 
-	if (prog->aux->max_rdonly_access > map->value_size) {
+	if (prog->aux->max_rdwr_access > map->value_size) {
 		err = -EACCES;
 		goto put_map;
 	}