fdt: Move fdt_fixup_ethernet to a common place

fdt: Move fdt_fixup_ethernet to a common place

With 3f66149d9fb4 we no longer have a common call fdt_fixup_ethernet.
This was fine to do on PowerPC as they largely had calls already in
ft_cpu_fixup.  On ARM however we largely relied on this call.  Rather
than introduce a large number of changes to ft_cpu_fixup /
ft_board_fixup we recognize that this is a common enough call that we
should be doing it in a central location.  Do it early enough that we
can do any further updates in ft_cpu_fixup / ft_board_fixup.

Cc: Gerd Hoffmann <[email protected]>
Cc: Chen-Yu Tsai <[email protected]>
Cc: Maxime Ripard <[email protected]>
Cc: Thomas Chou <[email protected]> (maintainer:NIOS)
Cc: York Sun <[email protected]> (maintainer:POWERPC MPC85XX)
Cc: Stefan Roese <[email protected]> (maintainer:POWERPC PPC4XX)
Cc: Simon Glass <[email protected]>
Cc: Joakim Tjernlund <[email protected]>
Fixes: 3f66149d9fb4 ("Remove extra fdt_fixup_ethernet() call")
Signed-off-by: Tom Rini <[email protected]>
Acked-by: Stefan Roese <[email protected]>
Acked-by: York Sun <[email protected]>
Reviewed-by: Simon Glass <[email protected]>