platform/x86: panasonic-laptop: 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 panasonic-laptop driver.

Fixes: de68372 ("platform/x86: panasonic-laptop: 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/3353471.5fSG56mABF@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/panasonic-laptop.c

@@ -981,11 +981,15 @@ static int acpi_pcc_hotkey_resume(struct device *dev)
 
 static int acpi_pcc_hotkey_probe(struct platform_device *pdev)
 {
-	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
 	struct backlight_properties props;
+	struct acpi_device *device;
 	struct pcc_acpi *pcc;
 	int num_sifr, result;
 
+	device = ACPI_COMPANION(&pdev->dev);
+	if (!device)
+		return -ENODEV;
+
 	num_sifr = acpi_pcc_get_sqty(device);
 
 	/*