net: miiphybb: Use container_of() in bb_miiphy_getbus()

net: miiphybb: Use container_of() in bb_miiphy_getbus()

Replace the name based look up in bb_miiphy_getbus() with trivial
container_of() call. This works because the struct bb_miiphy_bus
always embeds the matching struct mii_dev . This also makes the
code much simpler and more efficient.

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