net: phy: remove Kconfig symbol MDIO_DEVRES

MDIO_DEVRES is only set where PHYLIB/PHYLINK are set which
select MDIO_DEVRES. So we can remove this symbol.

Note: Due to circular module dependencies we can't simply
      make mdio_devres.c part of phylib.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://patch.msgid.link/27cba535-f507-4b32-84a3-0744c783a465@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>