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>

common/params.cc

@@ -251,7 +251,6 @@ std::unordered_map<std::string, uint32_t> keys = {
     {"CarMake", PERSISTENT},
     {"CarModel", PERSISTENT},
 
-    {"CarCruiseDisplayActual", PERSISTENT},
     {"CarSpeedLimit", PERSISTENT},
     
     {"CarSpeedLimitWarning", PERSISTENT},

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
 

selfdrive/car/hyundai/hyundaicanfd.py

@@ -2,7 +2,6 @@ from openpilot.common.numpy_fast import clip
 from openpilot.selfdrive.car import CanBusBase
 from openpilot.selfdrive.car.hyundai.values import HyundaiFlags
 
-from openpilot.common.params import Params
 
 class CanBus(CanBusBase):
   def __init__(self, CP, hda2=None, fingerprint=None) -> None:
@@ -127,9 +126,7 @@ def create_buttons(packer, CP, CAN, cnt, btn):
 
 def create_buttons_alt(packer, CP, CAN, cnt, btn, template):
   return
-  params_memory = Params("/dev/shm/params")
+
-  CarCruiseDisplayActual = params_memory.get_float("CarCruiseDisplayActual")
-  
   values = {
     "COUNTER": cnt,
     "NEW_SIGNAL_1": 0.0,