hardware: make set_display_power not abstract (#35061)

hardware: make set_dispaly_power not abstract

follow-up to https://github.com/commaai/openpilot/pull/35060#discussion_r2058829397

system/hardware/base.py

@@ -130,7 +130,6 @@ class HardwareBase(ABC):
   def get_thermal_config(self):
     return ThermalConfig()
 
-  @abstractmethod
   def set_display_power(self, on: bool):
     pass
 

system/hardware/pc/hardware.py

@@ -53,9 +53,6 @@ class Pc(HardwareBase):
   def shutdown(self):
     print("SHUTDOWN!")
 
-  def set_display_power(self, on):
-    pass
-
   def set_screen_brightness(self, percentage):
     pass