LU-19050 utils: fix get_root_path WANT condition

LU-19050 utils: fix get_root_path WANT condition

This patch fixes the WANT condition in get_root_path(), modified in
the previous patch, as get_root_path_fast() should not be called when
either WANT_INDEX or WANT_NID is set.

Fixes: fff7cd33bbb4 ("LU-19050 utils: Support long nid lists when getting fs info")
Signed-off-by: Marc Vef <mvef@whamcloud.com>
Change-Id: Ib801f9f2cc19eaeb1e3a5932391ccf7dc53b9f5e
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/59779
Reviewed-by: Aurelien Degremont <adegremont@nvidia.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>