net: davinci_mdio: Fix sparse warning

This patch fixes following sparse warning
davinci_mdio.c:85:27: warning: symbol 'default_pdata' was not declared. Should it be static?
Also makes the default_pdata as a constant.
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/davinci_mdio.c

@@ -82,7 +82,7 @@ struct davinci_mdio_regs {
 	}	user[0];
 };
 
-struct mdio_platform_data default_pdata = {
+static const struct mdio_platform_data default_pdata = {
 	.bus_freq = DEF_OUT_FREQ,
 };