mm/mapping_dirty_helpers: remove double Note in kerneldoc

make W=1 generates the following warning for mm/mapping_dirty_helpers.c

mm/mapping_dirty_helpers.c:325: warning: duplicate section name 'Note'

The helper function is very specific to one driver -- vmwgfx.  While the
two notes are separate, all of it needs to be taken into account when
using the helper so make it one note.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Dan Streetman <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/mapping_dirty_helpers.c

@@ -317,7 +317,7 @@ EXPORT_SYMBOL_GPL(wp_shared_mapping_range);
  * pfn_mkwrite(). And then after a TLB flush following the write-protection
  * pick up all dirty bits.
  *
- * Note: This function currently skips transhuge page-table entries, since
+ * This function currently skips transhuge page-table entries, since
  * it's intended for dirty-tracking on the PTE level. It will warn on
  * encountering transhuge dirty entries, though, and can easily be extended
  * to handle them as well.