mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage

Mostly direct substitution with occasional adjustment or removing
outdated comments.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ubifs/super.c

@@ -2237,7 +2237,7 @@ static int __init ubifs_init(void)
 	BUILD_BUG_ON(UBIFS_COMPR_TYPES_CNT > 4);
 
 	/*
-	 * We require that PAGE_CACHE_SIZE is greater-than-or-equal-to
+	 * We require that PAGE_SIZE is greater-than-or-equal-to
 	 * UBIFS_BLOCK_SIZE. It is assumed that both are powers of 2.
 	 */
 	if (PAGE_SIZE < UBIFS_BLOCK_SIZE) {