Move to mbedtls-2.10.0 tag

To build with the new release, we pick couple of more files from mbedTLS
library.

Change-Id: I77dfe5723284cb26d4e5c717fb0e6f6dd803cb6b
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/docs/user-guide.rst b/docs/user-guide.rst
index 7e50dc1..c7f7ef8 100644
--- a/docs/user-guide.rst
+++ b/docs/user-guide.rst
@@ -1074,7 +1074,7 @@
    is important to use a version that is compatible with TF-A and fixes any
    known security vulnerabilities. See `mbed TLS Security Center`_ for more
    information. The latest version of TF-A is tested with tag
-   ``mbedtls-2.6.0``.
+   ``mbedtls-2.10.0``.
 
    The ``drivers/auth/mbedtls/mbedtls_*.mk`` files contain the list of mbed TLS
    source files the modules depend upon.