i40e: Fix preempt count leak in napi poll tracepoint

In the Linux kernel, the following vulnerability has been resolved: i40e: Fix preempt count leak in napi poll tracepoint Using get_cpu() in the tracepoint assignment causes an obvious preempt count leak because nothing invokes put_cpu() to undo it: softirq: huh, entered softirq 3 NET_RX with preempt_count 00000100, exited with 00000101? This clearly has seen a lot of testing in the last 3+ years... Use smp_processor_id() instead.