Input: wistron_btns - use pm_sleep_ptr() to allow removal of ifdef CONFIG_PM guards

As the guards only apply to suspend and resume, #ifdef CONFIG_PM_SLEEP
would have been a tighter protection. As pm_sleep_ptr() lets the compiler
see the protected ops structure and callbacks but also lets the compiler
remove it as unused code if !CONFIG_PM_SLEEP this allows the #ifdef
guards to be removed, slightly simplifying the resulting code.

--
It seems likely that DEFINE_SIMPLE_DEV_PM_OPS() would work here but
I'd prefer not to make that change unless someone can confirm that the
extra callbacks registered will have no unwanted side effects in this
driver.

Signed-off-by: Jonathan Cameron <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/misc/wistron_btns.c

···
 	return 0;
 }
 
-#ifdef CONFIG_PM
 static int wistron_suspend(struct device *dev)
 {
 	if (have_wifi)
···
 	.poweroff	= wistron_suspend,
 	.restore	= wistron_resume,
 };
-#endif
 
 static struct platform_driver wistron_driver = {
 	.driver		= {
 		.name	= "wistron-bios",
-#ifdef CONFIG_PM
-		.pm	= &wistron_pm_ops,
-#endif
+		.pm	= pm_sleep_ptr(&wistron_pm_ops),
 	},
 	.probe		= wistron_probe,
 	.remove		= wistron_remove,