mt76: mt7915: fix aggr len debugfs node

Similar to mt7921, fix 802.11 aggr len debugfs reporting for mt7915 driver.

Fixes: e57b7901 ("mt76: add mac80211 driver for MT7915 PCIe-based chipsets")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/debugfs.c

@@ -124,7 +124,7 @@ mt7915_ampdu_stat_read_phy(struct mt7915_phy *phy,
 		range[i] = mt76_rr(dev, MT_MIB_ARNG(ext_phy, i));
 
 	for (i = 0; i < ARRAY_SIZE(bound); i++)
-		bound[i] = MT_MIB_ARNCR_RANGE(range[i / 4], i) + 1;
+		bound[i] = MT_MIB_ARNCR_RANGE(range[i / 4], i % 4) + 1;
 
 	seq_printf(file, "\nPhy %d\n", ext_phy);