mm/madvise: don't forget to leave lazy MMU mode in madvise_cold_or_pageout_pte_range()

We need to leave lazy MMU mode before unlocking.

Link: https://lkml.kernel.org/r/20240126032608.355899-1-senozhatsky@chromium.org
Fixes: b2f557a21bc8 ("mm/madvise: add cond_resched() in madvise_cold_or_pageout_pte_range()")
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jiexun Wang <wangjiexun@tinylab.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>