mmc: sdhci-brcmstb: Add shutdown callback

Shutdown controller and disable it's clocks to insure max power
savings in S5 on systems that leave power on.
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Link: https://lore.kernel.org/r/20200113210706.11972-5-alcooperx@gmail.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-brcmstb.c

@@ -161,6 +161,15 @@ static int sdhci_brcmstb_probe(struct platform_device *pdev)
 	return res;
 }
 
+static void sdhci_brcmstb_shutdown(struct platform_device *pdev)
+{
+	int ret;
+
+	ret = sdhci_pltfm_unregister(pdev);
+	if (ret)
+		dev_err(&pdev->dev, "failed to shutdown\n");
+}
+
 MODULE_DEVICE_TABLE(of, sdhci_brcm_of_match);
 
 static struct platform_driver sdhci_brcmstb_driver = {
@@ -171,6 +180,7 @@ static struct platform_driver sdhci_brcmstb_driver = {
 	},
 	.probe		= sdhci_brcmstb_probe,
 	.remove		= sdhci_pltfm_unregister,
+	.shutdown	= sdhci_brcmstb_shutdown,
 };
 
 module_platform_driver(sdhci_brcmstb_driver);