Update incorrect comment

Signed-off-by: Pengyu Lv <pengyu.lv@arm.com>
diff --git a/tests/compat.sh b/tests/compat.sh
index 6d09b4f..e520c31 100755
--- a/tests/compat.sh
+++ b/tests/compat.sh
@@ -1175,7 +1175,7 @@
             if [ $EXIT -eq 0 ]; then
                 RESULT=0
             else
-                # If the cipher isn't supported...
+                # If ti is NULL cipher ...
                 if grep 'Cipher is (NONE)' $CLI_OUT >/dev/null; then
                     RESULT=1
                 else