[Core] Serial-protocol: always clear receive queue on main half of split keyboard (#18419)

platforms/chibios/drivers/serial_protocol.c

@@ -102,15 +102,11 @@ static inline bool react_to_transaction(void) {
  * @return bool Indicates success of transaction.
  */
 bool soft_serial_transaction(int index) {
-    bool result = initiate_transaction((uint8_t)index);
-
-    if (unlikely(!result)) {
     /* Clear the receive queue, to start with a clean slate.
      * Parts of failed transactions or spurious bytes could still be in it. */
     serial_transport_driver_clear();
-    }
 
-    return result;
+    return initiate_transaction((uint8_t)index);
 }
 
 /**