xsk: Use struct_size() helper

Improve readability and maintainability by using the struct_size()
helper when allocating the AF_XDP rings.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1576759171-28550-13-git-send-email-magnus.karlsson@intel.com
1 file changed