mt76: mt7615: check return value of mt7615_eeprom_get_power_index

mt7615_eeprom_get_power_index can return negative error value.
Check mt7615_eeprom_get_power_index return value before using it

Signed-off-by: Lorenzo Bianconi <[email protected]>
Signed-off-by: Felix Fietkau <[email protected]>

mt7615/init.c

@@ -253,6 +253,9 @@ void mt7615_init_txpower(struct mt7615_dev *dev,
 			int index;
 
 			index = mt7615_eeprom_get_power_index(dev, chan, j);
+			if (index < 0)
+				continue;
+
 			target_power = max(target_power, eep[index]);
 		}