net: hix5hd2_gmac: avoid integer overload warning

BITS_RX_EN is an 'unsigned long' constant, so the ones complement of that
has bits set that do not fit into a 32-bit variable on 64-bit architectures,
which causes a harmless gcc warning:

drivers/net/ethernet/hisilicon/hix5hd2_gmac.c: In function 'hix5hd2_port_disable':
drivers/net/ethernet/hisilicon/hix5hd2_gmac.c:374:2: warning: large integer implicitly truncated to unsigned type [-Woverflow]
  writel_relaxed(~(BITS_RX_EN | BITS_TX_EN), priv->base + PORT_EN);

This adds a cast to (u32) to tell gcc that the code is indeed fine.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hix5hd2_gmac.c

@@ -371,7 +371,7 @@ static void hix5hd2_port_enable(struct hix5hd2_priv *priv)
 
 static void hix5hd2_port_disable(struct hix5hd2_priv *priv)
 {
-	writel_relaxed(~(BITS_RX_EN | BITS_TX_EN), priv->base + PORT_EN);
+	writel_relaxed(~(u32)(BITS_RX_EN | BITS_TX_EN), priv->base + PORT_EN);
 	writel_relaxed(0, priv->base + DESC_WR_RD_ENA);
 }