samples: psa_crypto: Add twister regex for attestation token

So far running twister tests didn't fail even though the sample failed
to receive the initial attestation token data.
Therefore this adds the regex lines that the samples prints if the
IAT data were received.

Signed-off-by: Markus Swarowsky <markus.swarowsky@nordicsemi.no>

samples/tfm_integration/psa_crypto/sample.yaml

@@ -13,6 +13,9 @@ tests:
         harness_config:
           type: multi_line
           regex:
+            - "System IAT size is: (.*)"
+            - "Requesting IAT with (.*) byte challenge."
+            - "IAT data received: (.*)"
             - "Retrieving public key for key #1"
             - "Signature verified"
             - "Destroyed persistent key #1"