mt76: set fops_tx_stats.owner to THIS_MODULE

If THIS_MODULE is not set, the module would be removed while debugfs is
being used.
It eventually makes kernel panic.

Fixes: e57b7901 ("mt76: add mac80211 driver for MT7915 PCIe-based chipsets")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/debugfs.c

@@ -233,6 +233,7 @@ static const struct file_operations fops_tx_stats = {
 	.read = seq_read,
 	.llseek = seq_lseek,
 	.release = single_release,
+	.owner = THIS_MODULE,
 };
 
 static int mt7915_read_temperature(struct seq_file *s, void *data)