Align tests/src and include/src with 3.6 version

Allow tests/src and include/src to be Mbed TLS version-agnostic by:
* Sometimes accepting both an MBEDTLS_ and a PSA_ config option
* Sometimes using the version number to gate alternatives

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/tests/src/drivers/test_driver_aead.c b/tests/src/drivers/test_driver_aead.c
index 9c0677a..6992a06 100644
--- a/tests/src/drivers/test_driver_aead.c
+++ b/tests/src/drivers/test_driver_aead.c
@@ -16,8 +16,12 @@
 #include "mbedtls/constant_time.h"
 
 #if defined(MBEDTLS_TEST_LIBTESTDRIVER1)
+#if MBEDTLS_VERSION_MAJOR < 4
+#include "libtestdriver1/library/psa_crypto_aead.h"
+#else
 #include "libtestdriver1/tf-psa-crypto/drivers/builtin/src/psa_crypto_aead.h"
 #endif
+#endif
 
 mbedtls_test_driver_aead_hooks_t
     mbedtls_test_driver_aead_hooks = MBEDTLS_TEST_DRIVER_AEAD_INIT;