Clean up usart class a bit

Core/Inc/usart.hpp

@@ -9,6 +9,10 @@
 #include "stm32f4xx_hal_uart.h"
 
 namespace driver::usart {
+
+constexpr const uint8_t TX_BUFSIZE{20};
+constexpr const uint8_t TX_TIMEOUT_MS{200};
+
 class Usart {
    public:
     explicit Usart(USART_TypeDef* usart, uint32_t baudRate, uint32_t wordLength, uint32_t stopBits,
@@ -23,6 +27,5 @@ class Usart {
     UART_HandleTypeDef mHandle{};
 
     void tx(std::string_view range);
-    void flush();
 };
 }  // namespace driver::usart