ar71xx: add a workaround for ar8316 not always driving the TA bit to low

AR8316 behind a GPIO bitbanged MDIO bus fails to drive the turnaround bit
to low despite returning a valid value. Ignore it and just use the
returned value anyway.

SVN-Revision: 28422

target/linux/ar71xx/patches-2.6.39/920-mdio_bitbang_ignore_ta_value.patch

@@ -0,0 +1,20 @@
+--- a/drivers/net/phy/mdio-bitbang.c
++++ b/drivers/net/phy/mdio-bitbang.c
+@@ -165,16 +165,7 @@ static int mdiobb_read(struct mii_bus *b
+ 
+ 	ctrl->ops->set_mdio_dir(ctrl, 0);
+ 
+-	/* check the turnaround bit: the PHY should be driving it to zero */
+-	if (mdiobb_get_bit(ctrl) != 0) {
+-		/* PHY didn't drive TA low -- flush any bits it
+-		 * may be trying to send.
+-		 */
+-		for (i = 0; i < 32; i++)
+-			mdiobb_get_bit(ctrl);
+-
+-		return 0xffff;
+-	}
++	mdiobb_get_bit(ctrl);
+ 
+ 	ret = mdiobb_get_num(ctrl, 16);
+ 	mdiobb_get_bit(ctrl);