staging: octeon: repair "fixed-link" support

The PHYs must be registered once in device probe function, not in device
open callback because it's only possible to register them once.

Fixes: a25e2780 ("staging: octeon: support fixed-link phys")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201016101858.11374-1-alexander.sverdlin@nokia.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>