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_signature.c b/tests/src/drivers/test_driver_signature.c
index 92ec93b..a6eef57 100644
--- a/tests/src/drivers/test_driver_signature.c
+++ b/tests/src/drivers/test_driver_signature.c
@@ -26,10 +26,16 @@
 #include "test/random.h"
 
 #if defined(MBEDTLS_TEST_LIBTESTDRIVER1)
+#if MBEDTLS_VERSION_MAJOR < 4
+#include "libtestdriver1/library/psa_crypto_ecp.h"
+#include "libtestdriver1/library/psa_crypto_hash.h"
+#include "libtestdriver1/library/psa_crypto_rsa.h"
+#else
 #include "libtestdriver1/tf-psa-crypto/drivers/builtin/src/psa_crypto_ecp.h"
 #include "libtestdriver1/tf-psa-crypto/drivers/builtin/src/psa_crypto_hash.h"
 #include "libtestdriver1/tf-psa-crypto/drivers/builtin/src/psa_crypto_rsa.h"
 #endif
+#endif
 
 #include <string.h>