Add ed25519 verification to sim

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/sim/src/image.rs b/sim/src/image.rs
index 99fb3fb..b5a68dd 100644
--- a/sim/src/image.rs
+++ b/sim/src/image.rs
@@ -1168,6 +1168,8 @@
             TlvGen::new_rsa3072_pss()
         } else if Caps::EcdsaP256.present() {
             TlvGen::new_ecdsa()
+        } else if Caps::Ed25519.present() {
+            TlvGen::new_ed25519()
         } else {
             TlvGen::new_hash_only()
         }