RDMA/mlx5: Refactor get_ts_format functions to simplify code

QPC, SQC and RQC timestamp formats and capabilities are always equal
because they represent general hardware support. So instead of code
duplication, let's merge them into general enum and logic.

Signed-off-by: Aharon Landau <aharonl@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>