sim: Test software rollback protection

Signed-off-by: Håkon Øye Amundsen <haakon.amundsen@nordicsemi.no>
Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/sim/src/caps.rs b/sim/src/caps.rs
index a63a343..f823b99 100644
--- a/sim/src/caps.rs
+++ b/sim/src/caps.rs
@@ -22,6 +22,7 @@
     Ed25519              = (1 << 9),
     EncEc256             = (1 << 10),
     SwapUsingMove        = (1 << 11),
+    DowngradePrevention  = (1 << 12),
 }
 
 impl Caps {