Tools: Fix script logging

Fix issue preventing scripts respecting --log_level argument, by adding
a non-default handler. Also, add script name to log output.

Change-Id: I100a5c29276d362dc38cd6c46f472e5991873293
Signed-off-by: Raef Coles <raef.coles@arm.com>
diff --git a/tools/modules/sign_data.py b/tools/modules/sign_data.py
index 7ef3cfb..7267348 100644
--- a/tools/modules/sign_data.py
+++ b/tools/modules/sign_data.py
@@ -17,7 +17,7 @@
 
 import argparse
 import logging
-logger = logging.getLogger("TF-M")
+logger = logging.getLogger("TF-M.{}".format(__name__))
 from arg_utils import *
 
 def _asn1_sig_to_raw(sig : bytes , curve : ec.EllipticCurve) -> bytes:
@@ -156,7 +156,8 @@
     add_arguments(parser, required=True)
 
     args = parser.parse_args()
-    logger.setLevel(args.log_level)
+    logging.getLogger("TF-M").setLevel(args.log_level)
+    logger.addHandler(logging.StreamHandler())
 
     config = parse_args(args)
     config |= parse_args_automatically(args, ["data"])