drm/xe/uapi: Crystal Reference Clock updates

First of all, let's remove the duplication.
But also, let's rename it to remove the word 'frequency'
out of it. In general, the first thing people think of frequency
is the frequency in which the GTs are operating to execute the
GPU instructions.

While this frequency here is a crystal reference clock frequency
which is the base of everything else, and in this case of this
uAPI it is used to calculate a better and precise timestamp.

v2: (Suggested by Jose) Remove the engine_cs and keep the GT info one
since it might be useful for other SRIOV cases where the engine_cs
will be zeroed. So, grabbing from the GT_LIST should be cleaner.

v3: Keep comment on put_user() call (José Roberto de Souza)

Cc: Matt Roper <matthew.d.roper@intel.com>
Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Cc: Jose Souza <jose.souza@intel.com>

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>