{net, ib}/mlx5: Make cache line size determination at runtime.

ARM 64B cache line systems have L1_CACHE_BYTES set to 128.
cache_line_size() will return the correct size.

Fixes: cf50b5efa2fe('net/mlx5_core/ib: New device capabilities
handling.')
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>