code_size_compare: handle deleted files and new files properly

'Removed' and 'NotCreated' should be displayed in new and old column
respectively. The value of delta is reflected on change column. This
commit handles the corner cases properly.

Signed-off-by: Yanray Wang <yanray.wang@arm.com>
diff --git a/scripts/code_size_compare.py b/scripts/code_size_compare.py
index 52e0345..53d859e 100755
--- a/scripts/code_size_compare.py
+++ b/scripts/code_size_compare.py
@@ -644,13 +644,15 @@
                 delta = new_attr - old_attr
                 change_attr = '{0:{1}}'.format(delta, '+' if delta else '')
             elif old_size:
-                new_attr = - old_size.__dict__[sect]
+                new_attr = 'Removed'
                 old_attr = old_size.__dict__[sect]
-                change_attr = 'Removed'
+                delta = - old_attr
+                change_attr = '{0:{1}}'.format(delta, '+' if delta else '')
             elif new_size:
                 new_attr = new_size.__dict__[sect]
                 old_attr = 'NotCreated'
-                change_attr = 'None'
+                delta = new_attr
+                change_attr = '{0:{1}}'.format(delta, '+' if delta else '')
             else:
                 # Should never happen
                 new_attr = 'Error'