net/mlx5e: Skip PPHCR register query if not supported by the device

Check the PCAM supported registers mask before querying the PPHCR
register, as it is not supported in older devices.

Fixes: 44907e7 ("net/mlx5e: Add logic to read RS-FEC histogram bin ranges from PPHCR")
Signed-off-by: Alexei Lazar <alazar@nvidia.com>
Reviewed-by: Yael Chemla <ychemla@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/1761136182-918470-3-git-send-email-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Alexei Lazar

drivers/net/ethernet/mellanox/mlx5/core/en_stats.c

@@ -1614,7 +1614,9 @@ void mlx5e_stats_fec_get(struct mlx5e_priv *priv,
 
 	fec_set_corrected_bits_total(priv, fec_stats);
 	fec_set_block_stats(priv, mode, fec_stats);
-	fec_set_histograms_stats(priv, mode, hist);
+
+	if (MLX5_CAP_PCAM_REG(priv->mdev, pphcr))
+		fec_set_histograms_stats(priv, mode, hist);
 }
 
 #define PPORT_ETH_EXT_OFF(c) \