net: phy: Micrel KSZ8061: fix errata solution not taking effect problem

KSZ8061 needs to write to a MMD register at driver initialization to fix
an errata.  This worked in 5.0 kernel but not in newer kernels.  The
issue is the main phylib code no longer resets PHY at the very beginning.
Calling phy resuming code later will reset the chip if it is already
powered down at the beginning.  This wipes out the MMD register write.
Solution is to implement a phy resume function for KSZ8061 to take care
of this problem.

Fixes: 232ba3a5 ("net: phy: Micrel KSZ8061: link failure after cable connect")
Signed-off-by: Tristram Ha <tristram.ha@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>