Remove unnecessary warning options

Both -Wmissing-field-initializers and -Wsign-compare are both covered by
-Wextra which is enabled at W=1 anyway. Therefore, the explicit options
are not required.

Change-Id: I2e7d95b5fc14af7c70895859a7ebbeac5bc0d2a4
Signed-off-by: Justin Chadwell <justin.chadwell@arm.com>
diff --git a/docs/process/security-hardening.rst b/docs/process/security-hardening.rst
index 1a5524f..646b7a1 100644
--- a/docs/process/security-hardening.rst
+++ b/docs/process/security-hardening.rst
@@ -37,8 +37,7 @@
   - W=2
 
     Adds ``Waggregate-return``, ``Wcast-align``, ``Wnested-externs``,
-    ``Wshadow``, ``Wlogical-op``, ``Wmissing-field-initializers`` and
-    ``Wsign-compare``.
+    ``Wshadow``, ``Wlogical-op``.
 
   - W=3