CVE-2024-36974 net/sched: taprio: always validate TCA_TAPRIO_ATTR_PRIOMAP

In the Linux kernel, the following vulnerability has been resolved:

net/sched: taprio: always validate TCA_TAPRIO_ATTR_PRIOMAP

If one TCA_TAPRIO_ATTR_PRIOMAP attribute has been provided,
taprio_parse_mqprio_opt() must validate it, or userspace
can inject arbitrary data to the kernel, the second time
taprio_change() is called.

First call (with valid attributes) sets dev->num_tc
to a non zero value.

Second call (with arbitrary mqprio attributes)
returns early from taprio_parse_mqprio_opt()
and bad things can happen.