dma: ste_dma40: Fixup system suspend/resume

Make sure to handle register context save/restore when needed from
system PM callbacks.

Previously we solely trusted the device to reside in in-active state
while the system suspend callback were invoked, which is just too
optimistic.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/ste_dma40.c

@@ -2945,7 +2945,11 @@ static int dma40_suspend(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct d40_base *base = platform_get_drvdata(pdev);
-	int ret = 0;
+	int ret;
+
+	ret = pm_runtime_force_suspend(dev);
+	if (ret)
+		return ret;
 
 	if (base->lcpa_regulator)
 		ret = regulator_disable(base->lcpa_regulator);
@@ -2958,10 +2962,13 @@ static int dma40_resume(struct device *dev)
 	struct d40_base *base = platform_get_drvdata(pdev);
 	int ret = 0;
 
-	if (base->lcpa_regulator)
+	if (base->lcpa_regulator) {
 		ret = regulator_enable(base->lcpa_regulator);
-
+		if (ret)
 			return ret;
+	}
+
+	return pm_runtime_force_resume(dev);
 }
 #endif