bus: mvebu-mbus: Remove name -> target, attribute mapping tables

This tables were used together with the name-based MBus window
creation API. Since that's has been removed, we can also remove
the tables.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>