smsc911x: avoid PHY being resumed when interface is not up

SMSC911x doesn't need mdiobus suspend/resume, that's why it sets
'mac_managed_pm'. However, setting it needs to be moved from init to
probe, so mdiobus PM functions will really never be called (e.g. when
the interface is not up yet during suspend/resume).

Fixes: 3ce9f2be

 ("net: smsc911x: Stop and start PHY during suspend and resume")
Suggested-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230327083138.6044-1-wsa+renesas@sang-engineering.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>