1. typos/spelling ;-)

2. removed prev_vma and find_vma_prev because the condition checked
   later was always true

3. moved the free_area_cache/mmap_base check into arch_unmap_area_topdown
   where i think it belongs.

4. removed the extra free_area_cache setting code in the while loop
   as it only has to be set when we actually (and successfully) return
   from this function.

The only visible change to the layout should be the following: