stmmac: prefetch right address

To support XDP, a headroom is prepended to the packet data.
Consider this offset when doing a prefetch.

Fixes: da5ec7f ("net: stmmac: refactor stmmac_init_rx_buffers for stmmac_reinit_rx_buffers")
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -5131,7 +5131,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 
 		/* Buffer is good. Go on. */
 
-		prefetch(page_address(buf->page));
+		prefetch(page_address(buf->page) + buf->page_offset);
 		if (buf->sec_page)
 			prefetch(page_address(buf->sec_page));