This was apparently not built for several years: Since a2535243e011,
optee_copy_fdt_nodes implicitly works against the U-Boot dt. We
therefore have to tweak its reference before using the function and
restore things afterwards.

If it had been built, actually trying it out would have failed next: We
need CONFIG_OPTEE_LIB to actually build the function that is primarily
being tested here. And we need to re-initialize target fdt, now that the
tests may run in random order.

Fixes: a2535243e011 ("lib: optee: migration optee_copy_fdt_nodes for OF_LIVE support")
Fixes: ba2feaf41435 ("test: Split optee tests into three functions")
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

Rather than having this condition defined separately for each suite,
bracket all options with 'if UNIT_TEST'.

Signed-off-by: Simon Glass <sjg@chromium.org>

OP-TEE can get supplied with a devicetree and will then insert
its firmware node and reserved-memory sections into it.
As this devicetree often is not the one supplied to a later
loaded kernel, a previous commit added functionality to transfer
these nodes onto that new devicetree.

To make sure this functionality stays intact, also add a test
for the transfer functionality.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>