i40e: set xdp_rxq_info::frag_size

i40e: set xdp_rxq_info::frag_size

i40e support XDP multi-buffer so it is supposed to use
__xdp_rxq_info_reg() instead of xdp_rxq_info_reg() and set the
frag_size. It can not be simply converted at existing callsite because
rx_buf_len could be un-initialized, so let us register xdp_rxq_info
within i40e_configure_rx_ring(), which happen to be called with already
initialized rx_buf_len value.

Commit 5180ff1364bc ("i40e: use int for i40e_status") converted 'err' to
int, so two variables to deal with return codes are not needed within
i40e_configure_rx_ring(). Remove 'ret' and use 'err' to handle status
from xdp_rxq_info registration.

Fixes: e213ced19bef ("i40e: add support for XDP multi-buffer Rx")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/r/20240124191602.566724-11-maciej.fijalkowski@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>