Add ed25519 verification to sim

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/sim/src/caps.rs b/sim/src/caps.rs
index f316fd6..fa7c41e 100644
--- a/sim/src/caps.rs
+++ b/sim/src/caps.rs
@@ -13,6 +13,7 @@
     EncKw                = (1 << 6),
     ValidatePrimarySlot  = (1 << 7),
     RSA3072              = (1 << 8),
+    Ed25519              = (1 << 9),
 }
 
 impl Caps {