platform/x86: fujitsu: Check ACPI_COMPANION() against NULL

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: 6da22b031a3c ("platform/x86: fujitsu: Convert laptop driver to a platform one")
Fixes: d5c9212ccfaa ("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>