wifi: mt76: add DMA mapping error check in mt76_alloc_txwi()

Add 'dma_mapping_error()' check in 'mt76_alloc_txwi()'.
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/dma.c

@@ -53,6 +53,11 @@ mt76_alloc_txwi(struct mt76_dev *dev)
 
 	addr = dma_map_single(dev->dma_dev, txwi, dev->drv->txwi_size,
 			      DMA_TO_DEVICE);
+	if (unlikely(dma_mapping_error(dev->dma_dev, addr))) {
+		kfree(txwi);
+		return NULL;
+	}
+
 	t = (struct mt76_txwi_cache *)(txwi + dev->drv->txwi_size);
 	t->dma_addr = addr;