maintainers: set QoS git tree for some ethdev files

The tree dpdk-next-tm does not exist anymore.
Traffic management and metering APIs, which are part of ethdev,
can be merged in the existing tree dpdk-next-qos.

Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Acked-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>