r8169: Fix spelling mistake: "tx_underun" -> "tx_underrun"

There is a spelling mistake in the struct field tx_underun, rename
it to tx_underrun.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://patch.msgid.link/20240909140021.64884-1-colin.i.king@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/realtek/r8169_main.c

@@ -578,7 +578,7 @@ struct rtl8169_counters {
 	__le64	rx_broadcast;
 	__le32	rx_multicast;
 	__le16	tx_aborted;
-	__le16	tx_underun;
+	__le16	tx_underrun;
 };
 
 struct rtl8169_tc_offsets {
@@ -1843,7 +1843,7 @@ static void rtl8169_get_ethtool_stats(struct net_device *dev,
 	data[9] = le64_to_cpu(counters->rx_broadcast);
 	data[10] = le32_to_cpu(counters->rx_multicast);
 	data[11] = le16_to_cpu(counters->tx_aborted);
-	data[12] = le16_to_cpu(counters->tx_underun);
+	data[12] = le16_to_cpu(counters->tx_underrun);
 }
 
 static void rtl8169_get_strings(struct net_device *dev, u32 stringset, u8 *data)