thermal: ti-soc-thermal: bandgap: Fix build warning if !CONFIG_PM_SLEEP

Fix following build warning if CONFIG_PM_SLEEP is not set:

drivers/thermal/ti-soc-thermal/ti-bandgap.c:1478:12: warning: 'ti_bandgap_suspend' defined but not used [-Wunused-function]
 static int ti_bandgap_suspend(struct device *dev)
            ^
drivers/thermal/ti-soc-thermal/ti-bandgap.c:1492:12: warning: 'ti_bandgap_resume' defined but not used [-Wunused-function]
 static int ti_bandgap_resume(struct device *dev)
            ^
Acked-by: NNishanth Menon <nm@ti.com>
Signed-off-by: NGrygorii Strashko <Grygorii.Strashko@linaro.org>
Signed-off-by: NEduardo Valentin <edubezval@gmail.com>

drivers/thermal/ti-soc-thermal/ti-bandgap.c

@@ -1402,7 +1402,7 @@ int ti_bandgap_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM
+#ifdef CONFIG_PM_SLEEP
 static int ti_bandgap_save_ctxt(struct ti_bandgap *bgp)
 {
 	int i;