doc: Set correct syntax highlighting style

Several code blocks do not specify a language for syntax
highlighting. This results in Sphinx using a default highlighter
which is Python.

This patch adds the correct language to each code block that doesn't
already specify it.

Change-Id: Icce1949aabfdc11a334a42d49edf55fa673cddc3
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
diff --git a/docs/components/sdei.rst b/docs/components/sdei.rst
index 8c08789..7b6cc91 100644
--- a/docs/components/sdei.rst
+++ b/docs/components/sdei.rst
@@ -224,7 +224,7 @@
 The SDEI dispatcher implementation provides ``sdei_dispatch_event()`` API for
 this purpose. The API has the following signature:
 
-::
+.. code:: c
 
         int sdei_dispatch_event(int ev_num);