mt76: mt7615: retry if mt7615_mcu_init returns -EAGAIN

mt7615_load_patch in mt7615/mcu.c sometimes fails with:
mt7622-wmac 18000000.wmac: Failed to get patch semaphore
and returns -EAGAIN. But this error is returned all the way up to
mt7615_init_work with no actual retrial performed, leaving a
broken wireless phy.
Wait a bit and retry for up to 10 times before giving up.
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

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

@@ -16,8 +16,15 @@ static void mt7615_init_work(struct work_struct *work)
 {
 	struct mt7615_dev *dev = container_of(work, struct mt7615_dev,
 					      mcu_work);
+	int i, ret;
 
-	if (mt7615_mcu_init(dev))
+	ret = mt7615_mcu_init(dev);
+	for (i = 0; (ret == -EAGAIN) && (i < 10); i++) {
+		msleep(200);
+		ret = mt7615_mcu_init(dev);
+	}
+
+	if (ret)
 		return;
 
 	mt7615_mcu_set_eeprom(dev);