tests: Update hapd_ctrl_set_error_cases RTS/fragmentation threshold

The previously used invalid values will become allowed with the
following commits, so change the test case to use values that both were
and will continue to be invalid to avoid unnecessary failures.

Signed-off-by: Jouni Malinen <j@w1.fi>

tests/hwsim/test_hapd_ctrl.py

@@ -354,9 +354,9 @@ def test_hapd_ctrl_set_error_cases(dev, apdev):
                "beacon_int 65536",
                "acs_num_scans 0",
                "acs_num_scans 101",
-               "rts_threshold -1",
-               "rts_threshold 2348",
-               "fragm_threshold -1",
+               "rts_threshold -2",
+               "rts_threshold 65536",
+               "fragm_threshold -2",
                "fragm_threshold 2347",
                "send_probe_response -1",
                "send_probe_response 2",