net/mlx5: Cleanup kernel-doc warnings

$ git ls-files *.[ch] | egrep drivers/net/ethernet/mellanox/ | \
        xargs scripts/kernel-doc -none

drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.h:57:
warning: Enum value 'MLX5_FPGA_ACCESS_TYPE_I2C' not described ...
drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.h:57:
warning: Enum value 'MLX5_FPGA_ACCESS_TYPE_DONTCARE' not described ...
drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.h:118:
warning: Function parameter or member 'cb_arg' not described ...
drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.h:160:
warning: Function parameter or member 'conn' not described ...
drivers/net/ethernet/mellanox/mlx5/core/fpga/sdk.h:160:
warning: Excess function parameter 'fdev' description ...

Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reported-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>