net: dsa: felix: fix ethtool 256-511 and 512-1023 TX packet counters

What the driver actually reports as 256-511 is in fact 512-1023, and the
TX packets in the 256-511 bucket are not reported. Fix that.

Fixes: 56051948 ("net: dsa: ocelot: add driver for Felix switch family")
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

drivers/net/dsa/ocelot/felix_vsc9959.c

@@ -602,7 +602,8 @@ static const struct ocelot_stat_layout vsc9959_stats_layout[] = {
 	{ .offset = 0x87,	.name = "tx_frames_below_65_octets", },
 	{ .offset = 0x88,	.name = "tx_frames_65_to_127_octets", },
 	{ .offset = 0x89,	.name = "tx_frames_128_255_octets", },
-	{ .offset = 0x8B,	.name = "tx_frames_256_511_octets", },
+	{ .offset = 0x8A,	.name = "tx_frames_256_511_octets", },
+	{ .offset = 0x8B,	.name = "tx_frames_512_1023_octets", },
 	{ .offset = 0x8C,	.name = "tx_frames_1024_1526_octets", },
 	{ .offset = 0x8D,	.name = "tx_frames_over_1526_octets", },
 	{ .offset = 0x8E,	.name = "tx_yellow_prio_0", },