Must call mbedtls_mpi_mod_modulus_init() before anything else in tests

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/tests/suites/test_suite_bignum_mod_raw.function b/tests/suites/test_suite_bignum_mod_raw.function
index ff766b9..4adccce 100644
--- a/tests/suites/test_suite_bignum_mod_raw.function
+++ b/tests/suites/test_suite_bignum_mod_raw.function
@@ -117,10 +117,12 @@
     mbedtls_mpi_uint *X = NULL;
     mbedtls_mpi_uint *Y = NULL;
     mbedtls_mpi_uint *buff_m = NULL;
-    mbedtls_mpi_mod_modulus m;
     size_t limbs_X;
     size_t limbs_Y;
 
+    mbedtls_mpi_mod_modulus m;
+    mbedtls_mpi_mod_modulus_init( &m );
+
     TEST_EQUAL( mbedtls_test_read_mpi_core( &X, &limbs_X, input_X ), 0 );
     TEST_EQUAL( mbedtls_test_read_mpi_core( &Y, &limbs_Y, input_Y ), 0 );
 
@@ -129,8 +131,6 @@
     size_t bytes = limbs * sizeof( mbedtls_mpi_uint );
     size_t copy_bytes = copy_limbs * sizeof( mbedtls_mpi_uint );
 
-    mbedtls_mpi_mod_modulus_init( &m );
-
     TEST_EQUAL( limbs_X, limbs_Y );
     TEST_ASSERT( copy_limbs <= limbs );
 
@@ -190,10 +190,12 @@
     mbedtls_mpi_uint *X = NULL;
     mbedtls_mpi_uint *Y = NULL;
     mbedtls_mpi_uint *buff_m = NULL;
-    mbedtls_mpi_mod_modulus m;
     size_t limbs_X;
     size_t limbs_Y;
 
+    mbedtls_mpi_mod_modulus m;
+    mbedtls_mpi_mod_modulus_init( &m );
+
     TEST_EQUAL( mbedtls_test_read_mpi_core( &tmp_X, &limbs_X, input_X ), 0 );
     TEST_EQUAL( mbedtls_test_read_mpi_core( &tmp_Y, &limbs_Y, input_Y ), 0 );
 
@@ -202,8 +204,6 @@
     size_t bytes = limbs * sizeof( mbedtls_mpi_uint );
     size_t copy_bytes = copy_limbs * sizeof( mbedtls_mpi_uint );
 
-    mbedtls_mpi_mod_modulus_init( &m );
-
     TEST_EQUAL( limbs_X, limbs_Y );
     TEST_ASSERT( copy_limbs <= limbs );