Adapt psasim

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/psa-client-server/psasim/test/start_server.sh b/tests/psa-client-server/psasim/test/start_server.sh
index fcc8a97..58ab850 100755
--- a/tests/psa-client-server/psasim/test/start_server.sh
+++ b/tests/psa-client-server/psasim/test/start_server.sh
@@ -8,7 +8,7 @@
 # The server creates some local files when it starts up so we can wait for this
 # event as signal that the server is ready so that we can start client(s).
 function wait_for_server_startup() {
-    while [ $(find . -name "psa_notify_*" | wc -l) -eq 0 ]; do
+    while [ -z $(find /tmp -maxdepth 1 -name "psa_notify_*" -printf 1 -quit) ]; do
         sleep 0.1
     done
 }