tty: serial: atmel: use macros instead of hardcoded values

Use UART_PM_STATE_ON, UART_PM_STATE_OFF instead of hardcoded values.

Reviewed-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211007112014.2332019-1-claudiu.beznea@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/atmel_serial.c

@@ -2084,7 +2084,7 @@ static void atmel_serial_pm(struct uart_port *port, unsigned int state,
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
 	switch (state) {
-	case 0:
+	case UART_PM_STATE_ON:
 		/*
 		 * Enable the peripheral clock for this serial port.
 		 * This is called on uart_open() or a resume event.
@@ -2094,7 +2094,7 @@ static void atmel_serial_pm(struct uart_port *port, unsigned int state,
 		/* re-enable interrupts if we disabled some on suspend */
 		atmel_uart_writel(port, ATMEL_US_IER, atmel_port->backup_imr);
 		break;
-	case 3:
+	case UART_PM_STATE_OFF:
 		/* Back up the interrupt mask and disable all interrupts */
 		atmel_port->backup_imr = atmel_uart_readl(port, ATMEL_US_IMR);
 		atmel_uart_writel(port, ATMEL_US_IDR, -1);