net/sched: taprio: align entry index attr validation with mqprio

Both taprio and mqprio have code to validate respective entry index
attributes. The validation is indented to ensure that the attribute is
present, and that it's value is in range, and that each value is only
used once.

The purpose of this patch is to align the implementation of taprio with
that of mqprio as there seems to be no good reason for them to differ.
For one thing, this way, bugs will be present in both or neither.

As a follow-up some consideration could be given to a common function
used by both sch.

No functional change intended.

Except of tdc run: the results of the taprio tests

  # ok 81 ba39 - Add taprio Qdisc to multi-queue device (8 queues)
  # ok 82 9462 - Add taprio Qdisc with multiple sched-entry
  # ok 83 8d92 - Add taprio Qdisc with txtime-delay
  # ok 84 d092 - Delete taprio Qdisc with valid handle
  # ok 85 8471 - Show taprio class
  # ok 86 0a85 - Add taprio Qdisc to single-queue device
  # ok 87 6f62 - Add taprio Qdisc with too short interval
  # ok 88 831f - Add taprio Qdisc with too short cycle-time
  # ok 89 3e1e - Add taprio Qdisc with an invalid cycle-time
  # ok 90 39b4 - Reject grafting taprio as child qdisc of software taprio
  # ok 91 e8a1 - Reject grafting taprio as child qdisc of offloaded taprio
  # ok 92 a7bf - Graft cbs as child of software taprio
  # ok 93 6a83 - Graft cbs as child of offloaded taprio

Cc: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: Maher Azzouzi <maherazz04@gmail.com>
Link: https://lore.kernel.org/netdev/20250723125521.GA2459@horms.kernel.org/


Signed-off-by: Simon Horman <horms@kernel.org>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Link: https://patch.msgid.link/20250725-taprio-idx-parse-v1-1-b582fffcde37@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>