When ice_add_special_words() fails, the 'rm' is not released, which will
lead to a memory leak. Fix this up by going to 'err_unroll' label.

Compile tested only.

Fixes: 8b032a55 ("ice: low level support for tunnels")
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>