eth: lan966x: don't clear unsupported stats

Commit 12c2d0a ("net: lan966x: add ethtool configuration and statistics")
added support for various standard stats. We should not clear the stats
which are not collected by the device. Core code uses a special
initializer to detect when device does not report given stat.

Acked-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20240613003222.3327368-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/microchip/lan966x/lan966x_ethtool.c

@@ -376,34 +376,26 @@ static void lan966x_get_eth_mac_stats(struct net_device *dev,
 		lan966x->stats[idx + SYS_COUNT_TX_PMAC_BC];
 	mac_stats->SingleCollisionFrames =
 		lan966x->stats[idx + SYS_COUNT_TX_COL];
-	mac_stats->MultipleCollisionFrames = 0;
 	mac_stats->FramesReceivedOK =
 		lan966x->stats[idx + SYS_COUNT_RX_UC] +
 		lan966x->stats[idx + SYS_COUNT_RX_MC] +
 		lan966x->stats[idx + SYS_COUNT_RX_BC];
 	mac_stats->FrameCheckSequenceErrors =
 		lan966x->stats[idx + SYS_COUNT_RX_CRC] +
 		lan966x->stats[idx + SYS_COUNT_RX_CRC];
-	mac_stats->AlignmentErrors = 0;
 	mac_stats->OctetsTransmittedOK =
 		lan966x->stats[idx + SYS_COUNT_TX_OCT] +
 		lan966x->stats[idx + SYS_COUNT_TX_PMAC_OCT];
 	mac_stats->FramesWithDeferredXmissions =
 		lan966x->stats[idx + SYS_COUNT_TX_MM_HOLD];
-	mac_stats->LateCollisions = 0;
-	mac_stats->FramesAbortedDueToXSColls = 0;
-	mac_stats->FramesLostDueToIntMACXmitError = 0;
-	mac_stats->CarrierSenseErrors = 0;
 	mac_stats->OctetsReceivedOK =
 		lan966x->stats[idx + SYS_COUNT_RX_OCT];
-	mac_stats->FramesLostDueToIntMACRcvError = 0;
 	mac_stats->MulticastFramesXmittedOK =
 		lan966x->stats[idx + SYS_COUNT_TX_MC] +
 		lan966x->stats[idx + SYS_COUNT_TX_PMAC_MC];
 	mac_stats->BroadcastFramesXmittedOK =
 		lan966x->stats[idx + SYS_COUNT_TX_BC] +
 		lan966x->stats[idx + SYS_COUNT_TX_PMAC_BC];
-	mac_stats->FramesWithExcessiveDeferral = 0;
 	mac_stats->MulticastFramesReceivedOK =
 		lan966x->stats[idx + SYS_COUNT_RX_MC];
 	mac_stats->BroadcastFramesReceivedOK =