ll_temac: Add support for phy_mii_ioctl

This patch enables the ioctl support for the driver. So userspace
programs like mii-tool can work.

Resend in merge window

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>