platform/x86: wireless-hotkey: 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 wireless-hotkey driver.

Fixes: 8507277 ("platform/x86: wireless-hotkey: 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/3899916.MHq7AAxBmi@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/wireless-hotkey.c

@@ -89,9 +89,14 @@ static void wl_notify(acpi_handle handle, u32 event, void *data)
 
 static int wl_probe(struct platform_device *pdev)
 {
+	struct acpi_device *adev;
 	struct wl_button *button;
 	int err;
 
+	adev = ACPI_COMPANION(&pdev->dev);
+	if (!adev)
+		return -ENODEV;
+
 	button = kzalloc_obj(struct wl_button);
 	if (!button)
 		return -ENOMEM;
@@ -104,8 +109,8 @@ static int wl_probe(struct platform_device *pdev)
 		kfree(button);
 		return err;
 	}
-	err = acpi_dev_install_notify_handler(ACPI_COMPANION(&pdev->dev),
-					      ACPI_DEVICE_NOTIFY, wl_notify, button);
+	err = acpi_dev_install_notify_handler(adev, ACPI_DEVICE_NOTIFY,
+					      wl_notify, button);
 	if (err) {
 		pr_err("Failed to install ACPI notify handler\n");
 		wireless_input_destroy(&pdev->dev);