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outdated comments.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/fs/dax.c b/fs/dax.c
index 1f95416..75ba46d 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1094,7 +1094,7 @@
  * you are truncating a file, the helper function dax_truncate_page() may be
  * more convenient.
  *
- * We work in terms of PAGE_CACHE_SIZE here for commonality with
+ * We work in terms of PAGE_SIZE here for commonality with
  * block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
  * took care of disposing of the unnecessary blocks.  Even if the filesystem
  * block size is smaller than PAGE_SIZE, we have to zero the rest of the page
@@ -1146,7 +1146,7 @@
  * Similar to block_truncate_page(), this function can be called by a
  * filesystem when it is truncating a DAX file to handle the partial page.
  *
- * We work in terms of PAGE_CACHE_SIZE here for commonality with
+ * We work in terms of PAGE_SIZE here for commonality with
  * block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem
  * took care of disposing of the unnecessary blocks.  Even if the filesystem
  * block size is smaller than PAGE_SIZE, we have to zero the rest of the page