dm9601: fix phy/eeprom write routine

Use correct bit positions in DM_SHARED_CTRL register for writes.

Michael Planes recently encountered a 'KY-RS9600 USB-LAN converter', which
came with a driver CD containing a Linux driver. This driver turns out to
be a copy of dm9601.c with symbols renamed and my copyright stripped.
That aside, it did contain 1 functional change in dm_write_shared_word(),
and after checking the datasheet the original value was indeed wrong
(read versus write bits).

On Michaels HW, this change bumps receive speed from ~30KB/s to ~900KB/s.
On other devices the difference is less spectacular, but still significant
(~30%).
Reported-by: NMichael Planes <michael.planes@free.fr>
CC: stable@kernel.org
Signed-off-by: NPeter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/dm9601.c

@@ -240,7 +240,7 @@ static int dm_write_shared_word(struct usbnet *dev, int phy, u8 reg, __le16 valu
 		goto out;
 
 	dm_write_reg(dev, DM_SHARED_ADDR, phy ? (reg | 0x40) : reg);
-	dm_write_reg(dev, DM_SHARED_CTRL, phy ? 0x1c : 0x14);
+	dm_write_reg(dev, DM_SHARED_CTRL, phy ? 0x1a : 0x12);
 
 	for (i = 0; i < DM_TIMEOUT; i++) {
 		u8 tmp;