net/mlx5: Pass flow steering objects to fs_cmd

Pass the flow steering objects instead of their attributes
to fs_cmd in order to decrease number of arguments and in
addition it will be used to update object fields.
Pass the flow steering root namespace instead of the device
so will have context to the namespace in the fs_cmd layer.

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>