feat(da): add libspdm version 3.3.0

libspdm is a sample implementation that follows the DMTF SPDM
specifications DSP0274 [1].

libspdm project provides libraries that RMM imports as an interface
library named rmm-lib-spdm_requester to implement SPMD requester.

There are few patch files added in libspdm for below changes:
- Includes mbedtls headers, config file from RMM Mbed TLS
- Compiles cryptlib_mbedtls library with RMM Mbed TLS config

[1] https://www.dmtf.org/dsp/DSP0274

Signed-off-by: Arunachalam Ganapathy <arunachalam.ganapathy@arm.com>
Change-Id: I977877de39d6fca65c4a6e03ed679221c8a4bb47
diff --git a/docs/readme.rst b/docs/readme.rst
index 3278e46..0383d1c 100644
--- a/docs/readme.rst
+++ b/docs/readme.rst
@@ -71,8 +71,9 @@
 
 The `TF-RMM`_ project requires to be linked with certain other 3rd party
 projects and they are to be cloned from their repositories into ``ext`` folder
-before building. The projects are `MbedTLS`_, `t_cose`_, `QCBOR`_ and
-`CppUTest`_.
+before building. The projects are `MbedTLS`_, `t_cose`_, `QCBOR`_,
+`CppUTest`_ and `libspdm`_. `libspdm`_ repository is fetched during config phase
+when RMM_CCA_DA build option is enabled.
 
 The project also contains files which are imported from other projects
 into the source tree and may have a different license. Such files with
@@ -128,5 +129,6 @@
 .. _License and Copyright for Contributions: https://tf-rmm.readthedocs.io/en/latest/process/contributing.html#license-and-copyright-for-contributions
 .. _Contributor's Guide: https://tf-rmm.readthedocs.io/en/latest/process/contributing.html
 .. _CppUTest: https://github.com/cpputest/cpputest.git
+.. _libspdm: https://github.com/DMTF/libspdm.git
 .. _Trusted Firmware: https://www.trustedfirmware.org/
 .. _TF-RMM: https://www.trustedfirmware.org/projects/tf-rmm/