docs: updated overall architecture diagram

Dropped the `ff-a-spm-sel2.png` and use `Hafnium_overview_SPMD.png`.

Signed-off-by: J-Alves <joao.alves@arm.com>
Change-Id: Icbb9cfda336a805a7041652617abdb9f9e49d105
diff --git a/docs/secure-partition-manager/secure-partition-manager.rst b/docs/secure-partition-manager/secure-partition-manager.rst
index 7546b81..a854582 100644
--- a/docs/secure-partition-manager/secure-partition-manager.rst
+++ b/docs/secure-partition-manager/secure-partition-manager.rst
@@ -39,7 +39,7 @@
 and SPMC, one or multiple secure partitions, with an optional
 Hypervisor:
 
-.. image:: ../resources/diagrams/ff-a-spm-sel2.png
+.. image:: ../resources/diagrams/Hafnium_overview_SPMD.png
 
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