Update tf-psa-crypto pointer to bring in doxygen pre-work

Signed-off-by: Felix Conway <felix.conway@arm.com>
diff --git a/tf-psa-crypto b/tf-psa-crypto
index d056817..694fa1b 160000
--- a/tf-psa-crypto
+++ b/tf-psa-crypto
@@ -1 +1 @@
-Subproject commit d056817e037e350320519613848309559909f581
+Subproject commit 694fa1b81cce46e8e160c8bda1a700f8c2a68586