drm/i915: Save and restore the GM45 FBC regs on suspend and resume.

This hasn't fixed the regressions we were testing against, but clearly
should be required.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/i915_drv.h

@@ -342,6 +342,7 @@ typedef struct drm_i915_private {
 	u32 savePFIT_CONTROL;
 	u32 save_palette_a[256];
 	u32 save_palette_b[256];
+	u32 saveDPFC_CB_BASE;
 	u32 saveFBC_CFB_BASE;
 	u32 saveFBC_LL_BASE;
 	u32 saveFBC_CONTROL;