memory: mvebu-devbus: Remove address decoding window workaround

Now that mbus device tree binding has been introduced, remove the address
decoding window management from this driver.
A suitable 'ranges' entry should be added to the devbus-compatible node in
the device tree, as described by the mbus binding documentation.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@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>