IB/rxe: use setup_timer to simplify the code

Use setup_timer function instead of initializing timer with the function
and data fields.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>