Move the quasi reduction fixing function to bignum_mod_raw

Rename the function to 'fix_quasi_reduction' to better suite its functionality.
Also changed the name prefix to suite for the new module.

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>

library/bignum_mod_raw_invasive.h

@@ -0,0 +1,47 @@
+/**
+ * \file bignum_mod_raw_invasive.h
+ *
+ * \brief Function declarations for invasive functions of Low-level
+ *        modular bignum.
+ */
+/**
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#ifndef MBEDTLS_BIGNUM_MOD_RAW_INVASIVE_H
+#define MBEDTLS_BIGNUM_MOD_RAW_INVASIVE_H
+
+#include "common.h"
+#include "mbedtls/bignum.h"
+#include "bignum_mod.h"
+
+/** Convert an MPI to its canonical representative.
+ *
+ * \note Currently handles the case when `N->int_rep` is
+ * MBEDTLS_MPI_MOD_REP_MONTGOMERY.
+ *
+ * \param[in,out] X     The address of the MPI to be converted. Must have the
+ *                      same number of limbs as \p N.
+ * \param[in]     N     The address of the modulus.
+ *
+ * \return      \c 0 if successful.
+ * \return      #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p N is invalid.
+ */
+MBEDTLS_STATIC_TESTABLE
+int mbedtls_mpi_mod_raw_fix_quasi_reduction(mbedtls_mpi_uint *X,
+                                            const mbedtls_mpi_mod_modulus *N);
+
+#endif /* MBEDTLS_BIGNUM_MOD_RAW_INVASIVE_H */