tty: atmel_serial: Use devm_platform_ioremap_resource()

Simplify the request port function by using a single call
to devm_platform_ioremap_resource().

This will also enhance the printing from /proc/iomem:

cat /proc/iomem | grep flexcom ; cat /proc/iomem | grep serial

f0004000-f00041ff : f0004000.flexcom flexcom@f0004000
f8020000-f80201ff : f8020000.flexcom flexcom@f8020000
f0004200-f00043ff : f0004200.serial serial@200
f8020200-f80203ff : f8020200.serial serial@200
fffff200-fffff3ff : fffff200.serial serial@fffff200

Signed-off-by: Mihai Sain <[email protected]>
Tested-by: Andrei Simion <[email protected]>
Reviewed-by: Hari Prasath Gujulan Elango <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Mihai Sain

drivers/tty/serial/atmel_serial.c

@@ -2419,17 +2419,11 @@ static void atmel_release_port(struct uart_port *port)
 static int atmel_request_port(struct uart_port *port)
 {
 	struct platform_device *mpdev = to_platform_device(port->dev->parent);
-	int size = resource_size(mpdev->resource);
-
-	if (!request_mem_region(port->mapbase, size, "atmel_serial"))
-		return -EBUSY;
 
 	if (port->flags & UPF_IOREMAP) {
-		port->membase = ioremap(port->mapbase, size);
-		if (port->membase == NULL) {
-			release_mem_region(port->mapbase, size);
-			return -ENOMEM;
-		}
+		port->membase = devm_platform_ioremap_resource(mpdev, 0);
+		if (IS_ERR(port->membase))
+			return PTR_ERR(port->membase);
 	}
 
 	return 0;