octeontx2-pf: htb offload support for Round Robin scheduling

When multiple traffic flows reach Transmit level with the same
priority, with Round robin scheduling traffic flow with the highest
quantum value is picked. With this support, the user can add multiple
classes with the same priority and different quantum. This patch
does necessary changes to support the same.

Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>