net: gianfar: Use __be64 * to store pointers to big endian values

Timestamp values are read using pointers to 64-bit big endian values.
But the type of these pointers is u64 *, host byte order.
Use __be64 * instead.

Flagged by Sparse:

.../gianfar.c:2212:60: warning: cast to restricted __be64
.../gianfar.c:2475:53: warning: cast to restricted __be64

Introduced by
commit cc772ab ("gianfar: Add hardware RX timestamping support").

Compile tested only.
No functional change intended.

Signed-off-by: Simon Horman <horms@kernel.org>
Reviewed-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Link: https://patch.msgid.link/20241011-gianfar-be64-v1-1-a77ebe972176@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/freescale/gianfar.c

@@ -2207,8 +2207,9 @@ static void gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
 
 		if (unlikely(do_tstamp)) {
 			struct skb_shared_hwtstamps shhwtstamps;
-			u64 *ns = (u64 *)(((uintptr_t)skb->data + 0x10) &
-					  ~0x7UL);
+			__be64 *ns;
+
+			ns = (__be64 *)(((uintptr_t)skb->data + 0x10) & ~0x7UL);
 
 			memset(&shhwtstamps, 0, sizeof(shhwtstamps));
 			shhwtstamps.hwtstamp = ns_to_ktime(be64_to_cpu(*ns));
@@ -2471,7 +2472,7 @@ static void gfar_process_frame(struct net_device *ndev, struct sk_buff *skb)
 	/* Get receive timestamp from the skb */
 	if (priv->hwts_rx_en) {
 		struct skb_shared_hwtstamps *shhwtstamps = skb_hwtstamps(skb);
-		u64 *ns = (u64 *) skb->data;
+		__be64 *ns = (__be64 *)skb->data;
 
 		memset(shhwtstamps, 0, sizeof(*shhwtstamps));
 		shhwtstamps->hwtstamp = ns_to_ktime(be64_to_cpu(*ns));