net/mlx4: Use ARRAY_SIZE to get an array's size

The ARRAY_SIZE macro is defined to get an array's size which is
more compact and more formal in linux source. Thus, we can replace
the long sizeof(arr)/sizeof(arr[0]) with the compact ARRAY_SIZE.

Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/20210817121106.44189-1-wangborong@cdjrlc.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>