stmmac: make function tables const

These tables only contain function pointers.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/stmmac/common.h b/drivers/net/stmmac/common.h
index dec7ce4..375ea19 100644
--- a/drivers/net/stmmac/common.h
+++ b/drivers/net/stmmac/common.h
@@ -235,9 +235,9 @@
 };
 
 struct mac_device_info {
-	struct stmmac_ops	*mac;
-	struct stmmac_desc_ops	*desc;
-	struct stmmac_dma_ops	*dma;
+	const struct stmmac_ops		*mac;
+	const struct stmmac_desc_ops	*desc;
+	const struct stmmac_dma_ops	*dma;
 	struct mii_regs mii;	/* MII register Addresses */
 	struct mac_link link;
 };