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/design/interrupt-framework-design.rst b/docs/design/interrupt-framework-design.rst
index 6f692b2..d4057ea 100644
--- a/docs/design/interrupt-framework-design.rst
+++ b/docs/design/interrupt-framework-design.rst
@@ -48,7 +48,7 @@
 The following constants define the various interrupt types in the framework
 implementation.
 
-::
+.. code:: c
 
     #define INTR_TYPE_S_EL1      0
     #define INTR_TYPE_EL3        1