scripts: convert remainging scripts to python3

Convert the remaining scripts to python3. Mostly done with 2to3 and
manual adjustements to the code afterwards.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
Acked-by: Jerome Forissier <jerome@forissier.org>
Tested-by: Jerome Forissier <jerome@forissier.org> (QEMU, QEMUv8)
diff --git a/scripts/gen_hashed_bin.py b/scripts/gen_hashed_bin.py
index 67b2b04..a76a62c 100755
--- a/scripts/gen_hashed_bin.py
+++ b/scripts/gen_hashed_bin.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # SPDX-License-Identifier: BSD-2-Clause
 #
 # Copyright (c) 2014-2017, Linaro Limited
@@ -75,7 +75,7 @@
         elif len(page) == 0:
             break
         else:
-            print("Error: short read, got " + repr(len(page)))
+            print("Error: short read, got {}".format(len(page)))
             sys.exit(1)
 
     inf.close()
@@ -88,7 +88,7 @@
 def get_args():
     parser = argparse.ArgumentParser()
     parser.add_argument('--arch', required=True,
-                        choices=arch_id.keys(),
+                        choices=list(arch_id.keys()),
                         help='Architecture')
 
     parser.add_argument('--flags',
@@ -149,8 +149,8 @@
         hashlib.sha256().digest_size
 
     if paged_input_size % (4 * 1024) != 0:
-        print("Error: pageable size not a multiple of 4K:" +
-              repr(paged_input_size))
+        print("Error: pageable size not a multiple of 4K: {}".format(
+            paged_input_size))
         sys.exit(1)
 
     init_size = pager_input_size + \