apple-gmux: Fix kconfig dependencies

Fix the dependencies of apple-gmux to prevent it from being built-in
when one or more of its dependencies is built as a module. Otherwise it
can fail to build due to missing symbols.

v2: Add dependency on ACPI to fix build failure when ACPI=n
Reported-by: NArun Raghavan <arun.raghavan@collabora.co.uk>
Signed-off-by: NSeth Forshee <seth.forshee@canonical.com>
Signed-off-by: NMatthew Garrett <mjg@redhat.com>

drivers/platform/x86/Kconfig

@@ -758,8 +758,11 @@ config SAMSUNG_Q10
 
 config APPLE_GMUX
 	tristate "Apple Gmux Driver"
+	depends on ACPI
 	depends on PNP
-	select BACKLIGHT_CLASS_DEVICE
+	depends on BACKLIGHT_CLASS_DEVICE
+	depends on BACKLIGHT_APPLE=n || BACKLIGHT_APPLE
+	depends on ACPI_VIDEO=n || ACPI_VIDEO
 	---help---
 	  This driver provides support for the gmux device found on many
 	  Apple laptops, which controls the display mux for the hybrid