[PATCH] mm: zap_pte_range dec rss

Small adjustment: zap_pte_range decrement its rss counts from 0 then finally
add, avoiding negations - we don't have or need a sub_mm_rss.

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