Clarify comments on state test.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index fe9e001..c556740 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -4002,7 +4002,8 @@
 
     psa_aead_abort( &operation );
 
-    /* Test for not sending any additional data or data (encrypt) */
+    /* Test for not sending any additional data or data after setting non zero
+     * lengths for them. (encrypt) */
 
     operation = psa_aead_operation_init( );
 
@@ -4022,7 +4023,8 @@
 
     psa_aead_abort( &operation );
 
-    /* Test for not sending any additional data or data (decrypt) */
+    /* Test for not sending any additional data or data after setting non-zero
+     * lengths for them. (decrypt) */
 
     operation = psa_aead_operation_init( );
 
@@ -4042,7 +4044,8 @@
 
     psa_aead_abort( &operation );
 
-    /* Test for not sending any additional data. */
+    /* Test for not sending any additional data after setting a non-zero length
+     * for it. */
 
     operation = psa_aead_operation_init( );