[PATCH next] drm/i915: fix build error without ACPI

[Chen Zhou <chenzhou10@huawei.com>]

If CONFIG_ACPI=n and CONFIG_BACKLIGHT_CLASS_DEVICE=m, compilation complains
with undefined references:

drivers/gpu/drm/i915/display/intel_panel.o: In function `intel_backlight_device_register':
intel_panel.c:(.text+0x4dd9): undefined reference to `backlight_device_register'
drivers/gpu/drm/i915/display/intel_panel.o: In function `intel_backlight_device_unregister':
intel_panel.c:(.text+0x4e96): undefined reference to `backlight_device_unregister'

This patch select BACKLIGHT_CLASS_DEVICE directly.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
---
 drivers/gpu/drm/i915/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
index ba95959..6b69dab 100644
--- a/drivers/gpu/drm/i915/Kconfig
+++ b/drivers/gpu/drm/i915/Kconfig
@@ -16,7 +16,7 @@ config DRM_I915
 	select IRQ_WORK
 	# i915 depends on ACPI_VIDEO when ACPI is enabled
 	# but for select to work, need to select ACPI_VIDEO's dependencies, ick
-	select BACKLIGHT_CLASS_DEVICE if ACPI
+	select BACKLIGHT_CLASS_DEVICE
 	select INPUT if ACPI
 	select ACPI_VIDEO if ACPI
 	select ACPI_BUTTON if ACPI
-- 
2.7.4