drm/xe/uapi: Differentiate WAIT_OP from WAIT_MASK

On one hand the WAIT_OP represents the operation use for waiting such
as ==, !=, > and so on. On the other hand, the mask is applied to the
value used for comparision. Split those two to bring clarity to the uapi.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>