We always pass in blk_trace_bio_get_cgid(q, bio) to blk_add_trace_bio().
Since both are readily available in the function already, kill the
argument.
Signed-off-by: NMarcos Paulo de Souza <marcos.souza.org@gmail.com>

Rewrote commit message.
Signed-off-by: NJens Axboe <axboe@kernel.dk>