Fix possible uninitialization error

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/tests/suites/test_suite_bignum_mod.function b/tests/suites/test_suite_bignum_mod.function
index 527146e..8ab8ccf 100644
--- a/tests/suites/test_suite_bignum_mod.function
+++ b/tests/suites/test_suite_bignum_mod.function
@@ -207,6 +207,9 @@
     mbedtls_mpi_mod_modulus m;
     mbedtls_mpi_mod_modulus_init( &m );
 
+    mbedtls_mpi_mod_modulus fake_m;
+    mbedtls_mpi_mod_modulus_init( &fake_m );
+
     TEST_EQUAL( test_read_modulus( &m, MBEDTLS_MPI_MOD_REP_MONTGOMERY, input_N ),
                 0 );
 
@@ -223,9 +226,6 @@
 
     TEST_EQUAL( mbedtls_mpi_mod_mul( &rX, &rA, &rB, &m ), exp_ret );
 
-    mbedtls_mpi_mod_modulus fake_m;
-    mbedtls_mpi_mod_modulus_init( &fake_m );
-
     /* Check when m is not initialized */
     TEST_EQUAL( mbedtls_mpi_mod_mul( &rX, &rA, &rB, &fake_m ),
                 MBEDTLS_ERR_MPI_BAD_INPUT_DATA );