dwc_eth_qos: constify net_device_ops structures

Check for net_device_ops structures that are only stored in the netdev_ops
field of a net_device structure.  This field is declared const, so
net_device_ops structures that have this property can be declared as const
also.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@r disable optional_qualifier@
identifier i;
position p;
@@
static struct net_device_ops i@p = { ... };

@ok@
identifier r.i;
struct net_device e;
position p;
@@
e.netdev_ops = &i@p;

@bad@
position p != {r.p,ok.p};
identifier r.i;
struct net_device_ops e;
@@
e@i@p

@depends on !bad disable optional_qualifier@
identifier r.i;
@@
static
+const
 struct net_device_ops i = { ... };
// </smpl>

The result of size on this file before the change is:
   text	      data     bss     dec         hex	  filename
  21623       1316      40   22979        59c3
   drivers/net/ethernet/synopsys/dwc_eth_qos.o

and after the change it is:
   text	     data        bss	    dec	    hex	filename
  22199       724         40      22963    59b3
   drivers/net/ethernet/synopsys/dwc_eth_qos.o
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/synopsys/dwc_eth_qos.c

@@ -2761,7 +2761,7 @@ static const struct ethtool_ops dwceqos_ethtool_ops = {
 	.set_link_ksettings = phy_ethtool_set_link_ksettings,
 };
 
-static struct net_device_ops netdev_ops = {
+static const struct net_device_ops netdev_ops = {
 	.ndo_open		= dwceqos_open,
 	.ndo_stop		= dwceqos_stop,
 	.ndo_start_xmit		= dwceqos_start_xmit,