samsung-laptop: fix config build error

Fix build failure when ACPI_VIDEO=m and SAMSUNG_LAPTOP=y.
The patch prevents that specific config combination.

drivers/built-in.o: In function `samsung_init':
samsung-laptop.c:(.init.text+0x128ff): undefined reference to `acpi_video_unregister'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Corentin Chary <corentin.chary@gmail.com>

build testing:
ACPI_VIDEO=m, SAMSUNG_LAPTOP=m: OK
ACPI_VIDEO=y, SAMSUNG_LAPTOP=m: OK
ACPI_VIDEO=y, SAMSUNG_LAPTOP=y: OK
ACPI=n, SAMSUNG_LAPTOP=y: OK
ACPI=n, SAMSUNG_LAPTOP=m: OK
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>

drivers/platform/x86/Kconfig

@@ -732,6 +732,7 @@ config SAMSUNG_LAPTOP
 	tristate "Samsung Laptop driver"
 	depends on X86
 	depends on RFKILL || RFKILL = n
+	depends on ACPI_VIDEO || ACPI_VIDEO = n
 	depends on BACKLIGHT_CLASS_DEVICE
 	select LEDS_CLASS
 	select NEW_LEDS