uboot-imx

doc: FIT image: fix incorrect examples of DT node unit address

The DT spec demands a unit-address of a node name to match the "reg"
property in that node. Newer dtc versions will throw warnings if this is
not the case.
Fix all occurences in the FIT image example files where this was not
observed, to not give bad examples to the reader.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>