Reorder _parse_block() parameters
Reorder _parse_block() parameters

Bit more readable to have the parent node and the previous node next to
each other.

Also rename 'prev_node' to just 'prev', to be consistent with 'parent'.
There's fewer parameters than in the past now, making it pretty easy to
follow anyway. Remove some inline parameter-related comments too.

ulfalizer/Kconfiglib,ulfalizer/Kconfiglib