Avoid potential bugs with fm10k_add_stat_strings and
fm10k_add_ethtool_stats by using a macro to calculate the ARRAY_SIZE
when passing. This helps ensure that the size is always correct.

Note that it assumes we only pass static const fm10k_stat arrays, and
that evaluation of the argument won't have side effects.
Signed-off-by: NJacob Keller <jacob.e.keller@intel.com>
Tested-by: NKrishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>