[BLE Client] Fix deadlock if connection loss ... (#7319)

... while readValue

Author: Rotzbua

Diff for: libraries/BLE/src/BLERemoteCharacteristic.cpp

@@ -247,6 +247,8 @@ void BLERemoteCharacteristic::gattClientEventHandler(esp_gattc_cb_event_t event,
 			break;
 
 		case ESP_GATTC_DISCONNECT_EVT:
+			// Cleanup semaphores to avoid deadlocks.
+			m_semaphoreReadCharEvt.give(1);
 			m_semaphoreWriteCharEvt.give(1);
 			break;