Improve variable name in mbedtls_mpi_lt_mpi_ct

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/bignum.c b/library/bignum.c
index aa5f818..de652c3 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -61,7 +61,7 @@
                           const mbedtls_mpi *Y,
                           unsigned *ret)
 {
-    mbedtls_ct_condition_t cond, X_is_negative, Y_is_negative, result;
+    mbedtls_ct_condition_t different_sign, X_is_negative, Y_is_negative, result;
 
     MPI_VALIDATE_RET(X != NULL);
     MPI_VALIDATE_RET(Y != NULL);
@@ -83,8 +83,8 @@
      * That is if X is negative (X_is_negative == 1), then X < Y is true and it
      * is false if X is positive (X_is_negative == 0).
      */
-    cond   = mbedtls_ct_bool_xor(X_is_negative, Y_is_negative); // non-zero if different sign
-    result = mbedtls_ct_bool_and(cond, X_is_negative);
+    different_sign = mbedtls_ct_bool_xor(X_is_negative, Y_is_negative); // non-zero if different sign
+    result = mbedtls_ct_bool_and(different_sign, X_is_negative);
 
     /*
      * Assuming signs are the same, compare X and Y. We switch the comparison
@@ -98,10 +98,11 @@
     mbedtls_ct_condition_t lt = mbedtls_mpi_core_lt_ct(p[i], p[i ^ 1], X->n);
 
     /*
-     * Store in result iff the signs are the same (i.e., iff cond == false). If
+     * Store in result iff the signs are the same (i.e., iff different_sign == false). If
      * the signs differ, result has already been set, so we don't change it.
      */
-    result = mbedtls_ct_bool_or(result, mbedtls_ct_bool_and(mbedtls_ct_bool_not(cond), lt));
+    result = mbedtls_ct_bool_or(result,
+                                mbedtls_ct_bool_and(mbedtls_ct_bool_not(different_sign), lt));
 
     *ret = mbedtls_ct_uint_if0(result, 1);