[qca-nss-qdisc] Resolved crashes in PPE qdisc

1. Avoid initiation of basic stats timer more than once.
2. Set NSS qdisc parent when attached to PPE qdisc.
3. Fix wrong flag check for unicast queue configuration.

Change-Id: I31d6326be1dd628b7bcae0eb8c1c8ae92fd7306d
Signed-off-by: Suruchi Agarwal <suruchia@codeaurora.org>
2 files changed