tests: add OP-TEE test suite

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>
diff --git a/test/Kconfig b/test/Kconfig
index 48a0e50..f53629a 100644
--- a/test/Kconfig
+++ b/test/Kconfig
@@ -33,4 +33,5 @@
 
 source "test/dm/Kconfig"
 source "test/env/Kconfig"
+source "test/optee/Kconfig"
 source "test/overlay/Kconfig"