usb: ehci-atmel: use __maybe_unused to hide pm functions

The ehci-atmel driver uses #ifdef to check for CONFIG_PM, but then
uses SIMPLE_DEV_PM_OPS, which leaves the references out when
CONFIG_PM_SLEEP is not defined, so we get a warning with
PM=y && PM_SLEEP=n:

drivers/usb/host/ehci-atmel.c:189:12: error: 'ehci_atmel_drv_suspend' defined but not used [-Werror=unused-function]
drivers/usb/host/ehci-atmel.c:203:12: error: 'ehci_atmel_drv_resume' defined but not used [-Werror=unused-function]

This removes the incorrect #ifdef and instead uses a __maybe_unused
annotation to let the compiler know it can silently drop
the function definition.

Signed-off-by: Arnd Bergmann <[e-mail]>
Acked-by: Nicolas Ferre <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/ehci-atmel.c

···
 	return 0;
 }
 
-#ifdef CONFIG_PM
-static int ehci_atmel_drv_suspend(struct device *dev)
+static int __maybe_unused ehci_atmel_drv_suspend(struct device *dev)
 {
 	struct usb_hcd *hcd = dev_get_drvdata(dev);
 	struct atmel_ehci_priv *atmel_ehci = hcd_to_atmel_ehci_priv(hcd);
···
 	return 0;
 }
 
-static int ehci_atmel_drv_resume(struct device *dev)
+static int __maybe_unused ehci_atmel_drv_resume(struct device *dev)
 {
 	struct usb_hcd *hcd = dev_get_drvdata(dev);
 	struct atmel_ehci_priv *atmel_ehci = hcd_to_atmel_ehci_priv(hcd);
···
 	atmel_start_clock(atmel_ehci);
 	return ehci_resume(hcd, false);
 }
-#endif
 
 #ifdef CONFIG_OF
 static const struct of_device_id atmel_ehci_dt_ids[] = {