lib: list_sort.c: add a blank line to avoid kernel-doc warnings

In order for a list to be recognized as such, blank lines
are required.

Solve those Sphinx warnings:

./lib/list_sort.c:162: WARNING: Unexpected indentation.
./lib/list_sort.c:163: WARNING: Block quote ends without a blank line; unexpected unindent.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

lib/list_sort.c

@@ -157,9 +157,11 @@ static void merge_final(void *priv, cmp_func cmp, struct list_head *head,
  *
  * The number of pending lists of size 2^k is determined by the
  * state of bit k of "count" plus two extra pieces of information:
+ *
  * - The state of bit k-1 (when k == 0, consider bit -1 always set), and
  * - Whether the higher-order bits are zero or non-zero (i.e.
  *   is count >= 2^(k+1)).
+ *
  * There are six states we distinguish.  "x" represents some arbitrary
  * bits, and "y" represents some arbitrary non-zero bits:
  * 0:  00x: 0 pending of size 2^k;           x pending of sizes < 2^k