ARM: mvebu: Remove the harcoded BootROM window allocation

The address decoding window to access the BootROM should not be
allocated programatically, but instead declared in the device tree.

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>