For tests, rename ASSERT_ALLOC() to TEST_CALLOC_OR_FAIL()

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/tests/suites/test_suite_bignum.function b/tests/suites/test_suite_bignum.function
index e088a73..db9c2e7 100644
--- a/tests/suites/test_suite_bignum.function
+++ b/tests/suites/test_suite_bignum.function
@@ -1507,7 +1507,7 @@
         full_stats = 0;
         stats_len = n_bits;
     }
-    ASSERT_ALLOC(stats, stats_len);
+    TEST_CALLOC_OR_FAIL(stats, stats_len);
 
     for (i = 0; i < (size_t) iterations; i++) {
         mbedtls_test_set_step(i);