cleanup: remove dead CarCruiseDisplayActual param

Audit of post-fork param additions found CarCruiseDisplayActual was
written every CAN cycle (gated) but only consumed by hyundaicanfd.py::
create_buttons_alt, which has `return` on line 1 and no active callers.
Write was pure waste. Removed registration, write path, cache field,
and the dead read.

Also dropped the now-unused `from openpilot.common.params import Params`
in hyundaicanfd.py.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

selfdrive/car/hyundai/carstate.py

@@ -51,7 +51,6 @@ class CarState(CarStateBase):
     # CLEARPILOT: cache to avoid per-cycle atomic writes to /dev/shm (eats CPU via fsync/flock)
     self._prev_car_speed_limit = None
     self._prev_car_is_metric = None
-    self._prev_car_cruise_display = None
 
     self.cruise_info = {}
 
@@ -223,11 +222,7 @@ class CarState(CarStateBase):
     if self.is_metric != self._prev_car_is_metric:
       self.params_memory.put("CarIsMetric", "1" if self.is_metric else "0")
       self._prev_car_is_metric = self.is_metric
-    car_cruise_display = cp_cruise.vl["SCC11"]["VSetDis"]
-    if car_cruise_display != self._prev_car_cruise_display:
-      self.params_memory.put_float("CarCruiseDisplayActual", car_cruise_display)
-      self._prev_car_cruise_display = car_cruise_display
-    
+
 
     return ret