[nrf noup] bootutil: Gives more logs on KMU not provisioned

Checks if the KMU has been provisioned, and add extra log if it has not.
Error 136 could theoretically be caused by something else, so the
extra logs is not phrased in a absolute manner.

Fixes: NCSDK-33559

Signed-off-by: Sigurd Hellesvik <[email protected]>

Author: hellesvik-nordic

boot/bootutil/src/ed25519_psa.c

@@ -126,6 +126,9 @@ int ED25519_verify(const uint8_t *message, size_t message_len,
         }
 
         BOOT_LOG_ERR("ED25519 signature verification failed %d", status);
+        if(status == PSA_ERROR_INVALID_HANDLE) {
+          BOOT_LOG_ERR("This error(-136) could mean that the KMU slot is not provisioned.");
+        }
     }
 
     return ret;