net: phy: remove leftovers from switch to linkmode bitmaps

We have some leftovers from the switch to linkmode bitmaps which
- have never been used
- are not used any longer
- have no user outside phy_device.c
So remove them.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://patch.msgid.link/5493b96e-88bb-4230-a911-322659ec5167@gmail.com


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