Tidy up reference to Mbed TLS in help message

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index b9ff1fb..0abbcf5 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -133,7 +133,7 @@
 
 pre_check_environment () {
     if in_mbedtls_repo || in_psa_crypto_repo; then :; else
-        echo "Must be run from Mbed TLS root" >&2
+        echo "Must be run from Mbed TLS / psa-crypto root" >&2
         exit 1
     fi
 }