tests/drivers/tee/optee: Switch from native_posix to native_sim

native_posix is being deprecated, let's switch this test to native_sim
instead.

Signed-off-by: Alberto Escolar Piedras <[email protected]>

Author: aescolar

tests/drivers/tee/optee/boards/native_posix_64.overlay renamed to tests/drivers/tee/optee/boards/native_sim_64.overlay

@@ -9,6 +9,6 @@ tests:
       - optee
     timeout: 500
     integration_platforms:
-      - native_posix/native/64
+      - native_sim/native/64
     platform_allow:
-      - native_posix/native/64
+      - native_sim/native/64