Rename ...if0 to ...else_0

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/bignum_core.c b/library/bignum_core.c
index 157ac07..a3c5403 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -463,7 +463,7 @@
     mbedtls_ct_condition_t do_add = mbedtls_ct_bool(cond);
 
     for (size_t i = 0; i < limbs; i++) {
-        mbedtls_mpi_uint add = mbedtls_ct_mpi_uint_if0(do_add, A[i]);
+        mbedtls_mpi_uint add = mbedtls_ct_mpi_uint_if_else_0(do_add, A[i]);
         mbedtls_mpi_uint t = c + X[i];
         c = (t < X[i]);
         t += add;