ethdev: fix TM API comment
ethdev: fix TM API comment

The rte_tm_node_wfq_weight_mode_update() API function operates on
non-leaf nodes, not leaf nodes.

Signed-off-by: Ben Shelton <626f623b1625bd99770c881335e4388b5b790774@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk