net: ravb: Fix dma_addr_t truncation in error case

In ravb_start_xmit(), ravb driver uses u32 variable to store result of
dma_map_single() call. Since ravb hardware has 32-bit address fields in
descriptors, this works properly when mapping is successful - it is
platform's job to provide mapping addresses that fit into hardware
limitations.

However, in failure case dma_map_single() returns DMA_MAPPING_ERROR
constant that is 64-bit when dma_addr_t is 64-bit. Storing this constant
in u32 leads to truncation, and further call to dma_mapping_error()
fails to notice the error.

Fix that by storing result of dma_map_single() in a dma_addr_t
variable.

Fixes: c156633f ("Renesas Ethernet AVB driver proper")
Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/ravb_main.c

@@ -1949,7 +1949,7 @@ static netdev_tx_t ravb_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	struct ravb_tstamp_skb *ts_skb;
 	struct ravb_tx_desc *desc;
 	unsigned long flags;
-	u32 dma_addr;
+	dma_addr_t dma_addr;
 	void *buffer;
 	u32 entry;
 	u32 len;