Merge branch 'net-phy-remove-fixed_phy_add-and-first-its-users'

Heiner Kallweit says:

====================
net: phy: remove fixed_phy_add and first its users

fixed_phy_add() has a number of problems/disadvantages:
- It uses phy address 0 w/o checking whether a fixed phy with this
  address exists already.
- A subsequent call to fixed_phy_register() would also use phy address 0,
  because fixed_phy_add() doesn't mark it as used.
- fixed_phy_add() is used from platform code, therefore requires that
  fixed phy code is built-in.

fixed_phy_add() has only two users
- coldfire/5272, using fec
- bcm47xx, using b44

So migrate fec and b44 to use fixed_phy_register_100fd(), afterwards
remove usage of fixed_phy_add() from the two platforms, and eventually
remove fixed_phy_add().
====================

Link: https://patch.msgid.link/0285fcb0-0fb5-4f6f-823c-7b6e85e28ba3@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>