tpm/tpm_crb: enter the low power state upon device suspend

This fix enables a platform to enter the idle state (suspend-to-idle)

The driver needs to request explicitly go_idle upon completion
from the pm suspend handler.
The runtime pm is disabled on suspend during prepare state by calling
pm_runtime_get_noresume, hence we cannot relay on runtime pm to leave
the device in low power state. Symmetrically cmdReady is called
upon resume.
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Siged-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

drivers/char/tpm/tpm_crb.c

@@ -502,10 +502,33 @@ static int crb_pm_runtime_resume(struct device *dev)
 
 	return crb_cmd_ready(dev, priv);
 }
+
+static int crb_pm_suspend(struct device *dev)
+{
+	int ret;
+
+	ret = tpm_pm_suspend(dev);
+	if (ret)
+		return ret;
+
+	return crb_pm_runtime_suspend(dev);
+}
+
+static int crb_pm_resume(struct device *dev)
+{
+	int ret;
+
+	ret = crb_pm_runtime_resume(dev);
+	if (ret)
+		return ret;
+
+	return tpm_pm_resume(dev);
+}
+
 #endif /* CONFIG_PM */
 
 static const struct dev_pm_ops crb_pm = {
-	SET_SYSTEM_SLEEP_PM_OPS(tpm_pm_suspend, tpm_pm_resume)
+	SET_SYSTEM_SLEEP_PM_OPS(crb_pm_suspend, crb_pm_resume)
 	SET_RUNTIME_PM_OPS(crb_pm_runtime_suspend, crb_pm_runtime_resume, NULL)
 };