octeontx2-pf: Qos: fix root node dwrr priority corruption

commit d9518edf734c0b273a051a8e979e2a17fd71866e from
git@git.assembla.com:cavium/WindRiver.linux.git

For PF netdev, dwrr priority of root node is static. In few scenarios,
driver is corrupting this value resulting in errors while reinstalling
htb nodes.

This patch fixes the same.

Fixes: 9f3fe44cee0b ("octeontx2-pf: Allow DWRR nodes at all priorities")
Change-Id: I6377c83652f7e703de8d1f0823a278a848340c74
Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/107613
Tested-by: sa_ip-sw-jenkins <sa_ip-sw-jenkins@marvell.com>
Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>