perf: remove unused __addr variable

now all calls to perf_trace_buf_submit() pass 0 as 4th
argument which will be repurposed in the next patch which will
change the meaning of 1st arg of perf_tp_event() to event_type

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>