Restore +1 in baud divider calculation

Author: facchinm

cores/arduino/UART.cpp

@@ -142,7 +142,7 @@ void UartClass::begin(unsigned long baud, uint16_t config)
     uint8_t oldSREG = SREG;
     cli();
 
-    baud_setting = (((8 * F_CPU_CORRECTED) / baud) ) / 2;
+    baud_setting = (((8 * F_CPU_CORRECTED) / baud) + 1) / 2;
     // Disable CLK2X
     (*_hwserial_module).CTRLB &= (~USART_RXMODE_CLK2X_gc);
     (*_hwserial_module).CTRLB |= USART_RXMODE_NORMAL_gc;