Doc: Remove useless escape characters

Just like has been done in the porting guide a couple of patches
earlier, kill all escaped underscore characters in all documents.

Change-Id: I7fb5b806412849761d9221a6ce3cbd95ec43d611
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/docs/auth-framework.rst b/docs/auth-framework.rst
index a46f946..7e401b7 100644
--- a/docs/auth-framework.rst
+++ b/docs/auth-framework.rst
@@ -209,7 +209,7 @@
 #. Tracking which images have been verified. In case an image is a part of
    multiple CoTs then it should be verified only once e.g. the Trusted World
    Key Certificate in the TBBR-Client spec. contains information to verify
-   SCP\_BL2, BL31, BL32 each of which have a separate CoT. (This
+   SCP_BL2, BL31, BL32 each of which have a separate CoT. (This
    responsibility has not been described in this document but should be
    trivial to implement).
 
@@ -627,7 +627,7 @@
 
 The CoT can be found in ``drivers/auth/tbbr/tbbr_cot.c``. This CoT consists of an
 array of image descriptors and it is registered in the framework using the macro
-``REGISTER_COT(cot_desc)``, where 'cot\_desc' must be the name of the array
+``REGISTER_COT(cot_desc)``, where 'cot_desc' must be the name of the array
 (passing a pointer or any other type of indirection will cause the registration
 process to fail).