net: miiphybb: Drop priv from struct bb_miiphy_bus

Remove the priv member from struct bb_miiphy_bus and its assignment
from drivers. This turns struct bb_miiphy_bus int struct mii_dev
wrapper, to be cleaned up next.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Paul Barker <paul.barker.ct@bp.renesas.com>

include/miiphy.h

@@ -74,7 +74,6 @@ struct bb_miiphy_bus_ops {
 };
 
 struct bb_miiphy_bus {
-	void *priv;
 	struct mii_dev mii;
 };