ptp: ocp: reject unsupported periodic output flags

The ptp_ocp_signal_from_perout() function supports PTP_PEROUT_DUTY_CYCLE
and PTP_PEROUT_PHASE. It does not support PTP_PEROUT_ONE_SHOT, but does not
reject a request with such an unsupported flag.

Add the appropriate check to ensure that unsupported requests are rejected
both for PTP_PEROUT_ONE_SHOT as well as any future flags.

Fixes: 1aa66a3 ("ptp: ocp: Program the signal generators via PTP_CLK_REQ_PEROUT")
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250312-jk-net-fixes-supported-extts-flags-v2-5-ea930ba82459@intel.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/ptp/ptp_ocp.c

@@ -2090,6 +2090,10 @@ ptp_ocp_signal_from_perout(struct ptp_ocp *bp, int gen,
 {
 	struct ptp_ocp_signal s = { };
 
+	if (req->flags & ~(PTP_PEROUT_DUTY_CYCLE |
+			   PTP_PEROUT_PHASE))
+		return -EOPNOTSUPP;
+
 	s.polarity = bp->signal[gen].polarity;
 	s.period = ktime_set(req->period.sec, req->period.nsec);
 	if (!s.period)