It's been five years now that KM_* kmap flags have been removed and that
we can call clear_highpage from any context.  So we remove prep_zero_pages
accordingly.
Signed-off-by: NAnisse Astier <anisse@astier.eu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>