platform / x86 / PM: Fix unused function warnings for CONFIG_PM_SLEEP

According to compiler warnings, quite some suspend/resume functions
in platform x86 drivers are not used for CONFIG_PM_SLEEP unset, so
add #ifdefs to prevent them from being built in that case.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/drivers/platform/x86/hdaps.c b/drivers/platform/x86/hdaps.c
index d9ab6f6..777c7e3 100644
--- a/drivers/platform/x86/hdaps.c
+++ b/drivers/platform/x86/hdaps.c
@@ -305,10 +305,12 @@
 	return 0;
 }
 
+#ifdef CONFIG_PM_SLEEP
 static int hdaps_resume(struct device *dev)
 {
 	return hdaps_device_init();
 }
+#endif
 
 static SIMPLE_DEV_PM_OPS(hdaps_pm, NULL, hdaps_resume);