Fix double free in case of test failure

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/tests/suites/test_suite_psa_crypto_memory.function b/tests/suites/test_suite_psa_crypto_memory.function
index cc87848..50539e8 100644
--- a/tests/suites/test_suite_psa_crypto_memory.function
+++ b/tests/suites/test_suite_psa_crypto_memory.function
@@ -107,7 +107,10 @@
 
 exit:
     mbedtls_free(local_input.buffer);
-    mbedtls_free(input);
+
+    if (local_input.buffer != input) {
+        mbedtls_free(input);
+    }
 }
 /* END_CASE */