net/mlx5: Fix ptp max frequency adjustment range

.max_adj of ptp_clock_info acts as an absolute value for the amount in ppb
that can be set for a single call of .adjfine. This means that a single
call to .getfine cannot be greater than .max_adj or less than -(.max_adj).
Provides correct value for max frequency adjustment value supported by
devices.

Fixes: 3d8c38af ("net/mlx5e: Add PTP Hardware Clock (PHC) support")
Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -681,7 +681,7 @@ static int mlx5_ptp_verify(struct ptp_clock_info *ptp, unsigned int pin,
 static const struct ptp_clock_info mlx5_ptp_clock_info = {
 	.owner		= THIS_MODULE,
 	.name		= "mlx5_ptp",
-	.max_adj	= 100000000,
+	.max_adj	= 50000000,
 	.n_alarm	= 0,
 	.n_ext_ts	= 0,
 	.n_per_out	= 0,