net: phy: use phy_init_hw instead of open-coding it

Use phy_init_hw() instead of open-coding it in phy_mii_ioctl(), this
improves consistenty and makes sure that we will not duplicate the same
routine somewhere else.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>