sfc: Add XDP frame size

This driver uses RX page-split when possible. It was recently fixed
in commit 86e85bf ("sfc: fix XDP-redirect in this driver") to
add needed tailroom for XDP-redirect.

After the fix efx->rx_page_buf_step is the frame size, with enough
head and tail-room for XDP-redirect.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158945335278.97035.14611425333184621652.stgit@firesoul

drivers/net/ethernet/sfc/rx.c

@@ -308,6 +308,7 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
 	xdp_set_data_meta_invalid(&xdp);
 	xdp.data_end = xdp.data + rx_buf->len;
 	xdp.rxq = &rx_queue->xdp_rxq_info;
+	xdp.frame_sz = efx->rx_page_buf_step;
 
 	xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp);
 	rcu_read_unlock();