platform/x86: acer-wireless: Check ACPI_COMPANION() against NULL

Every platform driver can be forced to match a device that doesn't match
its list of device IDs because of device_match_driver_override(), so
platform drivers that rely on the existence of a device's ACPI companion
object need to verify its presence.

Accordingly, add a requisite ACPI_COMPANION() check against NULL to the
platform/x86 acer-wireless driver.

Fixes: f7e6480 ("platform/x86: acer-wireless: Convert ACPI driver to a platform one")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/4746824.LvFx2qVVIh@rafael.j.wysocki
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: rafaeljw

drivers/platform/x86/acer-wireless.c

@@ -37,9 +37,14 @@ static void acer_wireless_notify(acpi_handle handle, u32 event, void *data)
 
 static int acer_wireless_probe(struct platform_device *pdev)
 {
+	struct acpi_device *adev;
 	struct input_dev *idev;
 	int ret;
 
+	adev = ACPI_COMPANION(&pdev->dev);
+	if (!adev)
+		return -ENODEV;
+
 	idev = devm_input_allocate_device(&pdev->dev);
 	if (!idev)
 		return -ENOMEM;
@@ -57,8 +62,7 @@ static int acer_wireless_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	return acpi_dev_install_notify_handler(ACPI_COMPANION(&pdev->dev),
-					       ACPI_DEVICE_NOTIFY,
+	return acpi_dev_install_notify_handler(adev, ACPI_DEVICE_NOTIFY,
 					       acer_wireless_notify,
 					       &pdev->dev);
 }