usb: musb: am35x: fix build warnings

This patch fixes the following build warnings:

drivers/usb/musb/am35x.c:573:12: warning: ‘am35x_suspend’ defined but
not used [-Wunused-function]
drivers/usb/musb/am35x.c:589:12: warning: ‘am35x_resume’ defined but not
used [-Wunused-function]
drivers/usb/musb/am35x.c:573:12: warning: ‘am35x_suspend’ defined but
not used [-Wunused-function]
drivers/usb/musb/am35x.c:589:12: warning: ‘am35x_resume’ defined but not
used [-Wunused-function]
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/am35x.c

@@ -569,7 +569,7 @@ static int am35x_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM
+#ifdef CONFIG_PM_SLEEP
 static int am35x_suspend(struct device *dev)
 {
 	struct am35x_glue	*glue = dev_get_drvdata(dev);