RDMA/mlx5: Fix timestamp default mode

1. Don't set the ts_format bit to default when it reserved - device is
   running in the old mode (free running).
2. XRC doesn't have a CQ therefore the ts format in the QP
   context should be default / free running.
3. Set ts_format to WQ.

Fixes: 2fe8d4b8 ("RDMA/mlx5: Fail QP creation if the device can not support the CQE TS")
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>