Relocate the bus structure definition into the MDIO source code area
of the ethernet driver. So if the real bus driver is forked from the
rest of the code only one area needs to be removed. Rename it to make
clear it belongs to the bus.
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Link: https://github.com/openwrt/openwrt/pull/18402
Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>