Py3 fixes for test scripts

Author: Olli-Pekka Puolitaival

TESTS/host_tests/rtc_reset.py

@@ -40,7 +40,7 @@ def setup(self):
         """Register callbacks required for the test"""
         self._error = False
         generator = self.rtc_reset_test()
-        generator.next()
+        next(generator)
 
         def run_gen(key, value, time):
             """Run the generator, and fail testing if the iterator stops"""

features/storage/filesystem/littlefs/TESTS/host_tests/unexpected_reset.py

@@ -38,7 +38,7 @@ def setup(self):
         """Register callbacks required for the test"""
         self._error = False
         generator = self.unexpected_reset_test()
-        generator.next()
+        next(generator)
 
         def run_gen(key, value, time):
             """Run the generator, and fail testing if the iterator stops"""