lib/mpi: Fix unused variable warnings

This patch removes a number of unused variables and marks others
as unused in order to silence compiler warnings about them.

Fixes: a8ea8bdd9df9 ("lib/mpi: Extend the MPI library")
Signed-off-by: Herbert Xu <[e-mail]>
Tested-by: Tianjia Zhang <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

lib/mpi/mpi-div.c

···
 	unsigned int normalization_steps;
 	mpi_limb_t q_limb;
 	mpi_ptr_t marker[5];
-	unsigned int marker_nlimbs[5];
 	int markidx = 0;
 
 	/* Ensure space is enough for quotient and remainder.
···
 		 * numerator would be gradually overwritten by the quotient limbs.
 		 */
 		if (qp == np) { /* Copy NP object to temporary space.  */
-			marker_nlimbs[markidx] = nsize;
 			np = marker[markidx++] = mpi_alloc_limb_space(nsize);
 			MPN_COPY(np, qp, nsize);
 		}
···
 		 * the most significant word.  Use temporary storage not to clobber
 		 * the original contents of the denominator.
 		 */
-		marker_nlimbs[markidx] = dsize;
 		tp = marker[markidx++] = mpi_alloc_limb_space(dsize);
 		mpihelp_lshift(tp, dp, dsize, normalization_steps);
 		dp = tp;
···
 		if (dp == rp || (quot && (dp == qp))) {
 			mpi_ptr_t tp;
 
-			marker_nlimbs[markidx] = dsize;
 			tp = marker[markidx++] = mpi_alloc_limb_space(dsize);
 			MPN_COPY(tp, dp, dsize);
 			dp = tp;

lib/mpi/mpi-internal.h

···
  */
 #define UDIV_QRNND_PREINV(q, r, nh, nl, d, di)				\
 	do {								\
-		mpi_limb_t _ql;						\
+		mpi_limb_t _ql __maybe_unused;				\
 		mpi_limb_t _q, _r;					\
 		mpi_limb_t _xh, _xl;					\
 		umul_ppmm(_q, _ql, (nh), (di));				\

lib/mpi/mpi-mul.c

···
 	int usign, vsign, sign_product;
 	int assign_wp = 0;
 	mpi_ptr_t tmp_limb = NULL;
-	unsigned int tmp_limb_nlimbs = 0;
 
 	if (u->nlimbs < v->nlimbs) {
 		/* Swap U and V. */
···
 	} else { /* Make U and V not overlap with W.	*/
 		if (wp == up) {
 			/* W and U are identical.  Allocate temporary space for U. */
-			tmp_limb_nlimbs = usize;
 			up = tmp_limb = mpi_alloc_limb_space(usize);
 			/* Is V identical too?  Keep it identical with U.  */
 			if (wp == vp)
···
 			MPN_COPY(up, wp, usize);
 		} else if (wp == vp) {
 			/* W and V are identical.  Allocate temporary space for V. */
-			tmp_limb_nlimbs = vsize;
 			vp = tmp_limb = mpi_alloc_limb_space(vsize);
 			/* Copy to the temporary space.  */
 			MPN_COPY(vp, wp, vsize);

lib/mpi/mpih-div.c

···
 {
 	mpi_size_t i;
 	mpi_limb_t n1, n0, r;
-	mpi_limb_t dummy;
+	mpi_limb_t dummy __maybe_unused;
 
 	/* Botch: Should this be handled at all?  Rely on callers?	*/
 	if (!dividend_size)
···
 {
 	mpi_size_t i;
 	mpi_limb_t n1, n0, r;
-	mpi_limb_t dummy;
+	mpi_limb_t dummy __maybe_unused;
 
 	if (!dividend_size)
 		return 0;