net: stmmac: dwmac-sun8i: Balance internal PHY power

net: stmmac: dwmac-sun8i: Balance internal PHY power

sun8i_dwmac_exit calls sun8i_dwmac_unpower_internal_phy, but
sun8i_dwmac_init did not call sun8i_dwmac_power_internal_phy. This
caused PHY power to remain off after a suspend/resume cycle. Fix this by
recording if PHY power should be restored, and if so, restoring it.

Fixes: b1a2a9eb0a76 ("net: stmmac: dwmac-sun8i: Handle integrated/external MDIOs")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: David S. Miller <davem@davemloft.net>