net/mlx5e: Replace 0-length array with flexible array
Zero-length arrays are deprecated[1]. Replace struct mlx5e_rx_wqe_cyc's
"data" 0-length array with a flexible array. Detected with GCC 13,
using -fstrict-flex-arrays=3:
drivers/net/ethernet/mellanox/mlx5/core/en_main.c: In function 'mlx5e_alloc_rq':
drivers/net/ethernet/mellanox/mlx5/core/en_main.c:827:42: warning: array subscript f is outside array bounds of 'struct mlx5_wqe_data_seg[0]' [-Warray-bounds=]
827 | wqe->data[f].byte_count = 0;
| ~~~~~~~~~^~~
In file included from drivers/net/ethernet/mellanox/mlx5/core/en/tc_ct.h:11,
from drivers/net/ethernet/mellanox/mlx5/core/eswitch.h:48,
from drivers/net/ethernet/mellanox/mlx5/core/en_main.c:42:
drivers/net/ethernet/mellanox/mlx5/core/en.h:250:39: note: while referencing 'data'
250 | struct mlx5_wqe_data_seg data[0];
| ^~~~