fix: remove PSA acronym when related to FF-A spec

The FF-A specification is no longer tied to Arm Platform Security
Architecture. Remove occurrences in the code base for the PSA acronym.

Change-Id: I5a96c59b6a3e4d9021517732209386813c9334aa
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/src/api.c b/src/api.c
index b713b7c..c911ebd 100644
--- a/src/api.c
+++ b/src/api.c
@@ -2131,7 +2131,7 @@
 	}
 
 	/*
-	 * Per PSA FF-A EAC spec section 4.4.1 the firmware framework supports
+	 * Per FF-A EAC spec section 4.4.1 the firmware framework supports
 	 * UP (migratable) or MP partitions with a number of vCPUs matching the
 	 * number of PEs in the system. It further states that MP partitions
 	 * accepting direct request messages cannot migrate.