net/mlx5: Fix turn-off PPS command

Fix a bug of uninitialized pin index when trying to turn off PPS out.

Fixes: de19cd6c ("net/mlx5: Move some PPS logic into helper functions")
Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Eran Ben Elisha <eranbe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c

@@ -495,15 +495,15 @@ static int mlx5_perout_configure(struct ptp_clock_info *ptp,
 		return -EINVAL;
 
 	field_select = MLX5_MTPPS_FS_ENABLE;
+	pin = ptp_find_pin(clock->ptp, PTP_PF_PEROUT, rq->perout.index);
+	if (pin < 0)
+		return -EBUSY;
+
 	if (on) {
 		bool rt_mode = mlx5_real_time_mode(mdev);
 		u32 nsec;
 		s64 sec;
 
-		pin = ptp_find_pin(clock->ptp, PTP_PF_PEROUT, rq->perout.index);
-		if (pin < 0)
-			return -EBUSY;
-
 		pin_mode = MLX5_PIN_MODE_OUT;
 		pattern = MLX5_OUT_PATTERN_PERIODIC;
 		ts.tv_sec = rq->perout.period.sec;