docs: soundwire: locking: fix tags for a code-block

There's an ascii artwork at Example 1 whose code-block is not properly
idented, causing those warnings.

    Documentation/driver-api/soundwire/locking.rst:50: WARNING: Inconsistent literal block quoting.
    Documentation/driver-api/soundwire/locking.rst:51: WARNING: Line block ends without a blank line.
    Documentation/driver-api/soundwire/locking.rst:55: WARNING: Inline substitution_reference start-string without end-string.
    Documentation/driver-api/soundwire/locking.rst:56: WARNING: Line block ends without a blank line.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/driver-api/soundwire/locking.rst

@@ -44,7 +44,9 @@ Message transfer.
      b. Transfer message (Read/Write) to Slave1 or broadcast message on
         Bus in case of bank switch.
 
-     c. Release Message lock ::
+     c. Release Message lock
+
+     ::
 
 	+----------+                    +---------+
 	|          |                    |         |