drm: Use spread spectrum when the bios tells us it's ok.

Lifted from the DDX modesetting.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 7325363..135a08f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -184,6 +184,8 @@
 	unsigned int lvds_dither:1;
 	unsigned int lvds_vbt:1;
 	unsigned int int_crt_support:1;
+	unsigned int lvds_use_ssc:1;
+	int lvds_ssc_freq;
 
 	struct drm_i915_fence_reg fence_regs[16]; /* assume 965 */
 	int fence_reg_start; /* 4 if userland hasn't ioctl'd us yet */