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outdated comments.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>
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index b02a7d5..4164bd6 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -708,9 +708,9 @@
 	from the address space.  This generally corresponds to either a
 	truncation, punch hole  or a complete invalidation of the address
 	space (in the latter case 'offset' will always be 0 and 'length'
-	will be PAGE_CACHE_SIZE). Any private data associated with the page
+	will be PAGE_SIZE). Any private data associated with the page
 	should be updated to reflect this truncation.  If offset is 0 and
-	length is PAGE_CACHE_SIZE, then the private data should be released,
+	length is PAGE_SIZE, then the private data should be released,
 	because the page must be able to be completely discarded.  This may
 	be done by calling the ->releasepage function, but in this case the
 	release MUST succeed.