net/mlx5: Build wq.o even if MLX5_CORE_EN is not selected

Both the ethernet and FPGA portions of MLX5 now require the wq functions,
and we get a link error when CONFIG_MLX5_CORE_EN is disabled:

drivers/net/ethernet/mellanox/mlx5/core/fpga/conn.o: In function `mlx5_fpga_conn_create_cq':
conn.c:(.text+0x10b3): undefined reference to `mlx5_cqwq_create'
conn.c:(.text+0x10c6): undefined reference to `mlx5_cqwq_get_size'
conn.c:(.text+0x12bc): undefined reference to `mlx5_cqwq_destroy'

Build wq.o even if MLX5_CORE_EN is not selected.

Fixes: 537a5057 ("net/mlx5: FPGA, Add high-speed connection routines")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ilan Tayari <ilant@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>