Add ed25519 verification to sim

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/boot/bootutil/src/caps.c b/boot/bootutil/src/caps.c
index f2126d7..96f27b3 100644
--- a/boot/bootutil/src/caps.c
+++ b/boot/bootutil/src/caps.c
@@ -35,6 +35,9 @@
 #if defined(MCUBOOT_SIGN_EC256)
     res |= BOOTUTIL_CAP_ECDSA_P256;
 #endif
+#if defined(MCUBOOT_SIGN_ED25519)
+    res |= BOOTUTIL_CAP_ED25519;
+#endif
 #if defined(MCUBOOT_OVERWRITE_ONLY)
     res |= BOOTUTIL_CAP_OVERWRITE_UPGRADE;
 #else