i40e: update xdp_rxq_info::frag_size for ZC enabled Rx queue

i40e: update xdp_rxq_info::frag_size for ZC enabled Rx queue

Now that i40e driver correctly sets up frag_size in xdp_rxq_info, let us
make it work for ZC multi-buffer as well. i40e_ring::rx_buf_len for ZC
is being set via xsk_pool_get_rx_frame_size() and this needs to be
propagated up to xdp_rxq_info.

Fixes: 1c9ba9c14658 ("i40e: xsk: add RX multi-buffer support")
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/r/20240124191602.566724-12-maciej.fijalkowski@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>