mm: remove the account_page_dirtied export

account_page_dirtied() is only used by our set_page_dirty() helpers and
should not be used anywhere else.

Link: http://lkml.kernel.org/r/20190605183702.30572-1-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>