net: macb: Fix offset error in gem_update_stats

[ Upstream commit 16c8a3a ]

hw_stats now has only one variable for tx_octets/rx_octets, so we should
only increment p once, not twice. This would cause the statistics to be
reported under the wrong categories in `ethtool -S --all-groups` (which
uses hw_stats) but not `ethtool -S` (which uses ethtool_stats).

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Fixes: f6af690 ("net: cadence: macb: Report standard stats")
Link: https://patch.msgid.link/20250825172134.681861-1-sean.anderson@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Sean Anderson

drivers/net/ethernet/cadence/macb_main.c

@@ -3090,7 +3090,7 @@ static void gem_update_stats(struct macb *bp)
 			/* Add GEM_OCTTXH, GEM_OCTRXH */
 			val = bp->macb_reg_readl(bp, offset + 4);
 			bp->ethtool_stats[i] += ((u64)val) << 32;
-			*(p++) += ((u64)val) << 32;
+			*p += ((u64)val) << 32;
 		}
 	}