ARM: dts: armada-xp-98dx3236: combine dfx server nodes

Rather than having a separate node for the dfx server add a reg property
to the parent node. This give some compatibility with the Marvell
supplied SDK.

As no upstream driver currently exists for this block and support for
this SoC is still quite fresh in the kernel it should not be necessary
to retain a backwards compatible binding.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>