net/mlx5e: Fix TX carrier errors report in get stats ndo

Symbol error during carrier counter from PPCNT was mistakenly reported as
TX carrier errors in get_stats ndo, although it's an RX counter.

Fixes: 269e6b3a

 ("net/mlx5e: Report additional error statistics in get stats ndo")
Signed-off-by: Gal Pressman <galp@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>