sh_eth: fix bitbang memory leak

sh_mdio_init() allocates pointer to 'struct bb_info' but only stores it locally,
so that sh_mdio_release() can't free it on driver unload.  Add the pointer to
'struct bb_info' to 'struct sh_eth_private', so that sh_mdio_init() can save
'bitbang' variable for sh_mdio_release() to be able to free it later...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/renesas/sh_eth.h b/drivers/net/ethernet/renesas/sh_eth.h
index bae84fd..e665567 100644
--- a/drivers/net/ethernet/renesas/sh_eth.h
+++ b/drivers/net/ethernet/renesas/sh_eth.h
@@ -705,6 +705,7 @@
 	const u16 *reg_offset;
 	void __iomem *addr;
 	void __iomem *tsu_addr;
+	struct bb_info *bitbang;
 	u32 num_rx_ring;
 	u32 num_tx_ring;
 	dma_addr_t rx_desc_dma;