usb: musb: blackfin: fix unused warnings on suspend/resume

When CONFIG_PM_SLEEP is disabled, SIMPLE_DEV_PM_OPS does not use
bfin_resume and bfin_suspend even if CONFIG_PM is enabled:

drivers/usb/musb/blackfin.c:602:12: warning: ‘bfin_resume’ defined but
not used [-Wunused-function]
 static int bfin_resume(struct device *dev)
            ^~~~~~~~~~~
drivers/usb/musb/blackfin.c:585:12: warning: ‘bfin_suspend’ defined but
not used [-Wunused-function]
 static int bfin_suspend(struct device *dev)
            ^~~~~~~~~~~~

The preprocessor condition should be on CONFIG_PM_SLEEP, not on CONFIG_PM.
However it is better to mark these functions as __maybe_unused.

Signed-off-by: Jérémy Lefaure <jeremy.lefaure@lse.epita.fr>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/blackfin.c

@@ -581,8 +581,7 @@ static int bfin_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM
-static int bfin_suspend(struct device *dev)
+static int __maybe_unused bfin_suspend(struct device *dev)
 {
 	struct bfin_glue	*glue = dev_get_drvdata(dev);
 	struct musb		*musb = glue_to_musb(glue);
@@ -599,7 +598,7 @@ static int bfin_suspend(struct device *dev)
 	return 0;
 }
 
-static int bfin_resume(struct device *dev)
+static int __maybe_unused bfin_resume(struct device *dev)
 {
 	struct bfin_glue	*glue = dev_get_drvdata(dev);
 	struct musb		*musb = glue_to_musb(glue);
@@ -608,7 +607,6 @@ static int bfin_resume(struct device *dev)
 
 	return 0;
 }
-#endif
 
 static SIMPLE_DEV_PM_OPS(bfin_pm_ops, bfin_suspend, bfin_resume);