sched: Dump configuration and statistics of dualpi2 qdisc

sched: Dump configuration and statistics of dualpi2 qdisc

The configuration and statistics dump of the DualPI2 Qdisc provides
information related to both queues, such as packet numbers and queuing
delays in the L-queue and C-queue, as well as general information such as
probability value, WRR credits, memory usage, packet marking counters, max
queue size, etc.

The following patch includes enqueue/dequeue for DualPI2.

Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Link: https://patch.msgid.link/20250722095915.24485-3-chia-yu.chang@nokia-bell-labs.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>