[FL-1318] Fix cyfral and metakom keys reading (#474)

applications/ibutton/helpers/key-reader.cpp

@@ -142,8 +142,10 @@ void KeyReader::comparator_trigger_callback(void* hcomp, void* comp_ctx) {
     if(hcomp == &hcomp1) {
         uint32_t current_dwt_value = DWT->CYCCNT;
 
-        _this->cyfral_decoder.process_front(hal_gpio_get_rfid_in_level(), current_dwt_value);
-        _this->metakom_decoder.process_front(hal_gpio_get_rfid_in_level(), current_dwt_value);
+        _this->cyfral_decoder.process_front(
+            hal_gpio_get_rfid_in_level(), current_dwt_value - last_dwt_value);
+        _this->metakom_decoder.process_front(
+            hal_gpio_get_rfid_in_level(), current_dwt_value - last_dwt_value);
 
         last_dwt_value = DWT->CYCCNT;
     }