memory-failure: use a folio in me_pagecache_clean()

Patch series "Convert aops->error_remove_page to ->error_remove_folio".

This is a memory-failure patch series which converts a lot of uses of page
APIs into folio APIs with the usual benefits.  


This patch (of 6):

Replaces three hidden calls to compound_head() with one visible one.
Fix up a few comments while I'm modifying this function.

Link: https://lkml.kernel.org/r/20231117161447.2461643-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20231117161447.2461643-2-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>