net: dp83867: Fix WoL SecureOn password

Fix the registers being written to as the values were being over written
when writing the same registers.

Fixes: caabee5b ("net: phy: dp83867: support Wake on LAN")
Signed-off-by: Dan Murphy <dmurphy@ti.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>