Add simulator support for RSA-3072 sigs

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/sim/src/image.rs b/sim/src/image.rs
index 58d5e25..92b052e 100644
--- a/sim/src/image.rs
+++ b/sim/src/image.rs
@@ -1141,6 +1141,8 @@
         // The non-encrypted configuration.
         if Caps::RSA2048.present() {
             TlvGen::new_rsa_pss()
+        } else if Caps::RSA3072.present() {
+            TlvGen::new_rsa3072_pss()
         } else if Caps::EcdsaP256.present() {
             TlvGen::new_ecdsa()
         } else {