ACPI, i915: build fix (v2)

drivers/built-in.o: In function `intel_opregion_init':
(.text+0x9d540): undefined reference to `acpi_video_register'

v2: move under DRM_I915 from DRM_I915_KMS

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>