platform/x86: fujitsu: 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 requisite ACPI_COMPANION() checks against NULL to the
platform/x86 fujitsu-laptop driver.

Fixes: 6da22b0 ("platform/x86: fujitsu: Convert laptop driver to a platform one")
Fixes: d5c9212 ("platform/x86: fujitsu: Convert backlight 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>
Acked-by: Jonathan Woithe <jwoithe@just42.net>
Link: https://patch.msgid.link/3430329.44csPzL39Z@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/fujitsu-laptop.c

@@ -530,10 +530,14 @@ static void acpi_fujitsu_bl_notify(acpi_handle handle, u32 event, void *data)
 
 static int acpi_fujitsu_bl_probe(struct platform_device *pdev)
 {
-	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
+	struct acpi_device *device;
 	struct fujitsu_bl *priv;
 	int ret;
 
+	device = ACPI_COMPANION(&pdev->dev);
+	if (!device)
+		return -ENODEV;
+
 	if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
 		return -ENODEV;
 
@@ -993,10 +997,14 @@ static void acpi_fujitsu_laptop_notify(acpi_handle handle, u32 event, void *data
 
 static int acpi_fujitsu_laptop_probe(struct platform_device *pdev)
 {
-	struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
 	struct fujitsu_laptop *priv;
+	struct acpi_device *device;
 	int ret, i = 0;
 
+	device = ACPI_COMPANION(&pdev->dev);
+	if (!device)
+		return -ENODEV;
+
 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;