mt76: mt7615: release mutex in mt7615_reset_test_set

Reduce scope of mutex_acquire/mutex_release in mt7615_reset_test_set
routine in order to fix the following static checker warning:

drivers/net/wireless/mediatek/mt76/mt7615/debugfs.c:179
mt7615_reset_test_set()
warn: inconsistent returns 'dev->mt76.mutex'.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: ea4906c4 ("mt76: mt7615: wake device before accessing regmap in debugfs")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

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

@@ -165,15 +165,14 @@ mt7615_reset_test_set(void *data, u64 val)
 	if (!mt7615_wait_for_mcu_init(dev))
 		return 0;
 
-	mt7615_mutex_acquire(dev);
-
 	skb = alloc_skb(1, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 
 	skb_put(skb, 1);
-	mt76_tx_queue_skb_raw(dev, 0, skb, 0);
 
+	mt7615_mutex_acquire(dev);
+	mt76_tx_queue_skb_raw(dev, 0, skb, 0);
 	mt7615_mutex_release(dev);
 
 	return 0;