ethtool: reformat kerneldoc for struct ethtool_fec_stats

The kerneldoc comment for struct ethtool_fec_stats attempts to describe the
"total" and "lanes" fields of the ethtool_fec_stat substructure in a way
leading to these warnings:

  ./include/linux/ethtool.h:424: warning: Excess struct member 'lane' description in 'ethtool_fec_stats'
  ./include/linux/ethtool.h:424: warning: Excess struct member 'total' description in 'ethtool_fec_stats'

Reformat the comment to retain the information while eliminating the
warnings.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -411,8 +411,10 @@ struct ethtool_pause_stats {
  *	not entire FEC data blocks. This is a non-standard statistic.
  *	Reported to user space as %ETHTOOL_A_FEC_STAT_CORR_BITS.
  *
- * @lane: per-lane/PCS-instance counts as defined by the standard
- * @total: error counts for the entire port, for drivers incapable of reporting
+ * For each of the above fields, the two substructure members are:
+ *
+ * - @lanes: per-lane/PCS-instance counts as defined by the standard
+ * - @total: error counts for the entire port, for drivers incapable of reporting
  *	per-lane stats
  *
  * Drivers should fill in either only total or per-lane statistics, core