net/mlx5: fs_core: Make find_closest_ft more generic

net/mlx5: fs_core: Make find_closest_ft more generic

As find_closest_ft_recursive is called to find the closest FT, the
first parameter of find_closest_ft can be changed from fs_prio to
fs_node. Thus this function is extended to find the closest FT for the
nodes of any type, not only prios, but also the sub namespaces.

Signed-off-by: Jianbo Liu <jianbol@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/d3962c2b443ec8dde7a740dc742a1f052d5e256c.1690803944.git.leonro@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>