mt76: mt7615: disable merge of OTP ROM data by default

The reference driver does not seem to enable it by default, only under certain
conditions, e.g. when a .bin file is loaded.
Make it opt-in via a device tree property for now, in case it is needed on some
boards.
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7615/eeprom.c

@@ -5,6 +5,7 @@
  *         Felix Fietkau <nbd@nbd.name>
  */
 
+#include <linux/of.h>
 #include "mt7615.h"
 #include "eeprom.h"
 
@@ -255,6 +256,11 @@ static void mt7622_apply_cal_free_data(struct mt7615_dev *dev)
 
 static void mt7615_cal_free_data(struct mt7615_dev *dev)
 {
+	struct device_node *np = dev->mt76.dev->of_node;
+
+	if (!np || !of_property_read_bool(np, "mediatek,eeprom-merge-otp"))
+		return;
+
 	switch (mt76_chip(&dev->mt76)) {
 	case 0x7622:
 		mt7622_apply_cal_free_data(dev);