misc: dell-laptop should depend on POWER_SUPPLY

dell-laptop makes use of the power supply class information to choose
which backlight interface to change. Add a depends on it.
Signed-off-by: NMatthew Garrett <mjg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/misc/Kconfig

@@ -217,6 +217,7 @@ config DELL_LAPTOP
 	depends on EXPERIMENTAL
 	depends on BACKLIGHT_CLASS_DEVICE
 	depends on RFKILL
+	depends on POWER_SUPPLY
 	default n
 	---help---
 	This driver adds support for rfkill and backlight control to Dell