net: ethernet: mtk-star-emac: set mac_managed_pm when probing

The below commit introduced a warning message when phy state is not in
the states: PHY_HALTED, PHY_READY, and PHY_UP.
commit 744d23c7 ("net: phy: Warn about incorrect mdio_bus_phy_resume() state")

mtk-star-emac doesn't need mdiobus suspend/resume. To fix the warning
message during resume, indicate the phy resume/suspend is managed by the
mac when probing.

Fixes: 744d23c7

 ("net: phy: Warn about incorrect mdio_bus_phy_resume() state")
Signed-off-by: Jian Hui Lee <jianhui.lee@canonical.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20240708065210.4178980-1-jianhui.lee@canonical.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>