Change mpi_core_exp_mod() constant time testing to be clearer

Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/tests/suites/test_suite_bignum_core.function b/tests/suites/test_suite_bignum_core.function
index cd80803..89c2282 100644
--- a/tests/suites/test_suite_bignum_core.function
+++ b/tests/suites/test_suite_bignum_core.function
@@ -1302,18 +1302,16 @@
               working_limbs);
 
     TEST_CALLOC(T, working_limbs);
+
+    /* Temporary because MEMSAN doesn't support assembly implementation see #1243 */
 #if !defined(MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN)
     TEST_CF_SECRET(A, A_limbs * sizeof(mbedtls_mpi_uint));
     TEST_CF_SECRET(N, N_limbs * sizeof(mbedtls_mpi_uint));
     TEST_CF_SECRET(E, E_limbs * sizeof(mbedtls_mpi_uint));
 #endif
     mbedtls_mpi_core_exp_mod(Y, A, N, N_limbs, E, E_limbs, R2, T);
-#if !defined(MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN)
+
     TEST_CF_PUBLIC(Y, N_limbs * sizeof(mbedtls_mpi_uint));
-    TEST_CF_PUBLIC(A, A_limbs * sizeof(mbedtls_mpi_uint));
-    TEST_CF_PUBLIC(N, N_limbs * sizeof(mbedtls_mpi_uint));
-    TEST_CF_PUBLIC(E, E_limbs * sizeof(mbedtls_mpi_uint));
-#endif
 
     TEST_EQUAL(0, memcmp(X, Y, N_limbs * sizeof(mbedtls_mpi_uint)));
 
@@ -1324,10 +1322,8 @@
 #endif
     /* Check when output aliased to input */
     mbedtls_mpi_core_exp_mod(A, A, N, N_limbs, E, E_limbs, R2, T);
-#if !defined(MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN)
-    TEST_CF_PUBLIC(A, A_limbs * sizeof(mbedtls_mpi_uint));
-#endif
 
+    TEST_CF_PUBLIC(A, A_limbs * sizeof(mbedtls_mpi_uint));
     TEST_EQUAL(0, memcmp(X, A, N_limbs * sizeof(mbedtls_mpi_uint)));
 
 exit: