net/mlx5e: mlx5e_fec_in_caps() returns a boolean

Returning errno is a bug, fix that.

Also fixes smatch warnings:
drivers/net/ethernet/mellanox/mlx5/core/en/port.c:453
mlx5e_fec_in_caps() warn: signedness bug returning '(-95)'

Fixes: 2132b71f ("net/mlx5e: Advertise globaly supported FEC modes")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Aya Levin <ayal@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en/port.c

@@ -490,11 +490,8 @@ bool mlx5e_fec_in_caps(struct mlx5_core_dev *dev, int fec_policy)
 	int err;
 	int i;
 
-	if (!MLX5_CAP_GEN(dev, pcam_reg))
-		return -EOPNOTSUPP;
-
-	if (!MLX5_CAP_PCAM_REG(dev, pplm))
-		return -EOPNOTSUPP;
+	if (!MLX5_CAP_GEN(dev, pcam_reg) || !MLX5_CAP_PCAM_REG(dev, pplm))
+		return false;
 
 	MLX5_SET(pplm_reg, in, local_port, 1);
 	err =  mlx5_core_access_reg(dev, in, sz, out, sz, MLX5_REG_PPLM, 0, 0);