net/sched: mqprio: fix stack out-of-bounds write in tc entry parsing

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

net/sched: mqprio: fix stack out-of-bounds write in tc entry parsing

TCA_MQPRIO_TC_ENTRY_INDEX is validated using NLA_POLICY_MAX(NLA_U32, TC_QOPT_MAX_QUEUE), which allows the value TC_QOPT_MAX_QUEUE (16). This leads to a 4-byte out-of-bounds stack write in the fp[] array, which only has room for 16 elements (0–15).

Fix this by changing the policy to allow only up to TC_QOPT_MAX_QUEUE - 1.