stm32: standard bauds to 115200

See also be1d296 stm32: serial use 115200
In that commit we mostly replaced 38400, now we've cleaned up all of
them to be consistent.

examples/stm32/f1/lisa-m-2/spi_dma/spi_dma.c

@@ -287,7 +287,7 @@ static void usart_setup(void)
 		      GPIO_CNF_INPUT_FLOAT, GPIO_USART2_RX);
 
 	/* Setup UART parameters. */
-	usart_set_baudrate(USART2, 9600);
+	usart_set_baudrate(USART2, 115200);
 	usart_set_databits(USART2, 8);
 	usart_set_stopbits(USART2, USART_STOPBITS_1);
 	usart_set_mode(USART2, USART_MODE_TX_RX);