mt76: mt7921: wake the device before dumping power table

Always wake the device up before dumping the single_sku power table
otherwise the device can hang.

Fixes: ea29acc9 ("mt76: mt7921: add dumping Tx power table")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7921/debugfs.c

@@ -184,7 +184,10 @@ mt7921_txpwr(struct seq_file *s, void *data)
 	struct mt7921_txpwr txpwr;
 	int ret;
 
+	mt7921_mutex_acquire(dev);
 	ret = mt7921_get_txpwr_info(dev, &txpwr);
+	mt7921_mutex_release(dev);
+
 	if (ret)
 		return ret;