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

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

esphome/components/ble_client/sensor/ble_sensor.cpp

@@ -11,8 +11,6 @@ namespace ble_client {
 
 static const char *const TAG = "ble_sensor";
 
-uint32_t BLESensor::hash_base() { return 343459825UL; }
-
 void BLESensor::loop() {}
 
 void BLESensor::dump_config() {

esphome/components/ble_client/sensor/ble_sensor.h

@@ -37,7 +37,6 @@ class BLESensor : public sensor::Sensor, public PollingComponent, public BLEClie
   uint16_t handle;
 
  protected:
-  uint32_t hash_base() override;
   float parse_data_(uint8_t *value, uint16_t value_len);
   optional<data_to_value_t> data_to_value_func_{};
   bool notify_;