serial: 8250_early: Convert literals to use defines

Use existing defines for the serial register values in 8250_early.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221125130509.8482-7-ilpo.jarvinen@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_early.c

@@ -136,11 +136,11 @@ static void __init init_port(struct earlycon_device *device)
 	unsigned char c;
 	unsigned int ier;
 
-	serial8250_early_out(port, UART_LCR, 0x3);	/* 8n1 */
+	serial8250_early_out(port, UART_LCR, UART_LCR_WLEN8);		/* 8n1 */
 	ier = serial8250_early_in(port, UART_IER);
 	serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); /* no interrupt */
 	serial8250_early_out(port, UART_FCR, 0);	/* no fifo */
-	serial8250_early_out(port, UART_MCR, 0x3);	/* DTR + RTS */
+	serial8250_early_out(port, UART_MCR, UART_MCR_DTR | UART_MCR_RTS);
 
 	if (port->uartclk) {
 		divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud);