mfd: intel-lpss: Fix too early PM enablement in the ACPI ->probe()

The runtime PM callback may be called as soon as the runtime PM facility
is enabled and activated. It means that ->suspend() may be called before
we finish probing the device in the ACPI case. Hence, NULL pointer
dereference:

  intel-lpss INT34BA:00: IRQ index 0 not found
  BUG: kernel NULL pointer dereference, address: 0000000000000030
  ...
  Workqueue: pm pm_runtime_work
  RIP: 0010:intel_lpss_suspend+0xb/0x40 [intel_lpss]

To fix this, first try to register the device and only after that enable
runtime PM facility.

Fixes: 4b45efe852 ("mfd: Add support for Intel Sunrisepoint LPSS devices")
Reported-by: Orlando Chamberlain <redecorating@protonmail.com>
Reported-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Aditya Garg <gargaditya08@live.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211101190008.86473-1-andriy.shevchenko@linux.intel.com

drivers/mfd/intel-lpss-acpi.c

@@ -136,6 +136,7 @@ static int intel_lpss_acpi_probe(struct platform_device *pdev)
 {
 	struct intel_lpss_platform_info *info;
 	const struct acpi_device_id *id;
+	int ret;
 
 	id = acpi_match_device(intel_lpss_acpi_ids, &pdev->dev);
 	if (!id)
@@ -149,10 +150,14 @@ static int intel_lpss_acpi_probe(struct platform_device *pdev)
 	info->mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	info->irq = platform_get_irq(pdev, 0);
 
+	ret = intel_lpss_probe(&pdev->dev, info);
+	if (ret)
+		return ret;
+
 	pm_runtime_set_active(&pdev->dev);
 	pm_runtime_enable(&pdev->dev);
 
-	return intel_lpss_probe(&pdev->dev, info);
+	return 0;
 }
 
 static int intel_lpss_acpi_remove(struct platform_device *pdev)