RDMA cgroup registration routine always returns success, so simplify
function to be void and run clang formatter over whole CONFIG_CGROUP_RDMA
art of core_priv.h.

This reduces unwinding error path for regular registration and future net
namespace change functionality for rdma device.
Signed-off-by: NParav Pandit <parav@mellanox.com>
Signed-off-by: NLeon Romanovsky <leonro@mellanox.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>