Fix get_token_map in case of unknown claim

Change-Id: I79c531ccd51af0d144bb8eb28945c26e1b6e1903
Signed-off-by: Mate Toth-Pal <mate.toth-pal@arm.com>
diff --git a/iat-verifier/tests/test_utils.py b/iat-verifier/tests/test_utils.py
index 8059139..e08d3a2 100644
--- a/iat-verifier/tests/test_utils.py
+++ b/iat-verifier/tests/test_utils.py
@@ -76,6 +76,7 @@
             check_p_header=check_p_header,
             lower_case_key=False)
     token_item.verify()
+    token_item.get_token_map()
     return token_item
 
 def create_and_read_iat(data_dir, source_name, verifier):