net-next: stmmac: add optional setup function

Instead of adding more ifthen logic for adding a new mac_device_info
setup function, it is easier to add a function pointer to the function
needed.

Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index f158273..c80c9c3 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3933,7 +3933,9 @@ static int stmmac_hw_init(struct stmmac_priv *priv)
 	struct mac_device_info *mac;
 
 	/* Identify the MAC HW device */
-	if (priv->plat->has_gmac) {
+	if (priv->plat->setup) {
+		mac = priv->plat->setup(priv);
+	} else if (priv->plat->has_gmac) {
 		priv->dev->priv_flags |= IFF_UNICAST_FLT;
 		mac = dwmac1000_setup(priv->ioaddr,
 				      priv->plat->multicast_filter_bins,