mtd: nand: atmel: mark resume function __maybe_unused

The newly added suspend/resume support causes a harmless warning:

drivers/mtd/nand/atmel/nand-controller.c:2513:12: error: 'atmel_nand_controller_resume' defined but not used [-Werror=unused-function]

This shuts up the warning with a __maybe_unused annotation.

Fixes: b107007a7114 ("mtd: nand: atmel: Add PM ops")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/atmel/nand-controller.c

@@ -2510,7 +2510,7 @@ static int atmel_nand_controller_remove(struct platform_device *pdev)
 	return nc->caps->ops->remove(nc);
 }
 
-static int atmel_nand_controller_resume(struct device *dev)
+static __maybe_unused int atmel_nand_controller_resume(struct device *dev)
 {
 	struct atmel_nand_controller *nc = dev_get_drvdata(dev);
 	struct atmel_nand *nand;