RDMA/mlx5: Support real-time timestamp directly from the device

Currently, if the user asks for a real-time timestamp, the device will
return a free-running one, and the timestamp will be translated to
real-time in the user-space.

When the device supports only real-time timestamp and not free-running,
the creation of the QP will fail even though the user needs supported the
real-time one. To prevent this, we will return the real-time timestamp
directly from the device.

Link: https://lore.kernel.org/r/c6cfc8e6f038575c5c2de6505830f7e74e4de80d.1623829775.git.leonro@nvidia.com


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