Use cls variable in classmethod

Signed-off-by: Michael Buesch <m@bues.ch>
tests: Use word for indirect block access

Signed-off-by: Michael Buesch <m@bues.ch>
Add check for offset operator width

Signed-off-by: Michael Buesch <m@bues.ch>
Remove AwlDbOffset

Use AwlOffset instead

Signed-off-by: Michael Buesch <m@bues.ch>