Cleanup deprecated EntityBase::hash_base() (#3525)

Co-authored-by: Maurice Makaay <mmakaay1@xs4all.net>

esphome/components/binary_sensor/binary_sensor.cpp

@@ -69,7 +69,6 @@ void BinarySensor::add_filters(const std::vector<Filter *> &filters) {
   }
 }
 bool BinarySensor::has_state() const { return this->has_state_; }
-uint32_t BinarySensor::hash_base() { return 1210250844UL; }
 bool BinarySensor::is_status_binary_sensor() const { return false; }
 
 }  // namespace binary_sensor