unmap_vma doesn't amount to much, let's put it inside unmap_vma_list.  Except
it doesn't unmap anything, unmap_region just did the unmapping: rename it to
remove_vma_list.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>