fm10k: add helper functions to set strings and data for ethtool stats

fm10k: add helper functions to set strings and data for ethtool stats

Reduce duplicate code and the amount of indentation by adding
fm10k_add_stat_strings and fm10k_add_ethtool_stats functions which help
add fm10k_stat structures to the ethtool stats callbacks. This helps
increase ease of use for future stat additions, and increases code
readability. Skip handling of the per-queue stats as these will be
reworked in a following patch.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Orabug: 25394529
(cherry picked from commit d2e0721b18f320232dc36a0e4cc7beb620e8c9bd)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>