mm: get rid of odd jump labels in find_mergeable_anon_vma()

Quoted 7 lines · linmiaohe

From: Miaohe Lin <[email protected]>

The jump labels try_prev and none are not really needed in find_mergeable_anon_vma(), eliminate them to improve readability. -v2:
Fix commit descriptions and further simplify the code as suggested by David Hildenbrand and John Hubbard.

Admin point: the above three lines will end up in the commit log, which is probably not what you intended. If, instead, you put them below the "---" line, then they will act as comments about the patch, and won't show up in the commit log.