Remove reference to removed |RSA_FLAG_NO_CONSTTIME| flag.

Change-Id: I0bfdccf009772d4ff8cd419758ab5bfae95f5cc5
Reviewed-on: https://boringssl-review.googlesource.com/6530
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/crypto/rsa/rsa_impl.c b/crypto/rsa/rsa_impl.c
index bee7f22..b1cfaa6 100644
--- a/crypto/rsa/rsa_impl.c
+++ b/crypto/rsa/rsa_impl.c
@@ -636,7 +636,7 @@
     BIGNUM *p = NULL, *q = NULL;
 
     /* Make sure BN_mod_inverse in Montgomery intialization uses the
-     * BN_FLG_CONSTTIME flag (unless RSA_FLAG_NO_CONSTTIME is set) */
+     * BN_FLG_CONSTTIME flag. */
     BN_init(&local_p);
     p = &local_p;
     BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);