psasim: Rename kill_server.sh to kill_servers.sh

Rename kill_server.sh to kill_servers.sh as it
kills all started PSA servers.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 7499651..4ff538a 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -1105,7 +1105,7 @@
     (
         cd tests
         msg "terminate server and cleanup"
-        psa-client-server/psasim//test/kill_server.sh
+        psa-client-server/psasim//test/kill_servers.sh
 
         # Remove temporary files and logs
         rm -f psa_notify_*