mm: fix Documentation/vm/hmm.rst Sphinx warnings

Fix Sphinx warnings in Documentation/vm/hmm.rst by using "::" notation and
inserting a blank line.  Also add a missing ';'.

  Documentation/vm/hmm.rst:292: WARNING: Unexpected indentation.
  Documentation/vm/hmm.rst:300: WARNING: Unexpected indentation.

Link: http://lkml.kernel.org/r/c5995359-7c82-4e47-c7be-b58a4dda0953@infradead.org
Fixes: 023a019a ("mm/hmm: add default fault flags to avoid the need to pre-fill pfns arrays")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/vm/hmm.rst

@@ -288,15 +288,17 @@ For instance if the device flags for device entries are:
     WRITE (1 << 62)
 
 Now let say that device driver wants to fault with at least read a range then
-it does set:
-    range->default_flags = (1 << 63)
+it does set::
+
+    range->default_flags = (1 << 63);
     range->pfn_flags_mask = 0;
 
 and calls hmm_range_fault() as described above. This will fill fault all page
 in the range with at least read permission.
 
 Now let say driver wants to do the same except for one page in the range for
-which its want to have write. Now driver set:
+which its want to have write. Now driver set::
+
     range->default_flags = (1 << 63);
     range->pfn_flags_mask = (1 << 62);
     range->pfns[index_of_write] = (1 << 62);