drm/i915: hw state readout for i9xx dplls

In addition to existing stuff we also need to track DPLL_MD on gen4
and vlv. This is prep work so that we can move the dpll enable
sequence out from the ->mode_set callback into the crtc enabling
functions.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index dfb10fe..e9c8b58 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -144,6 +144,7 @@
 
 struct intel_dpll_hw_state {
 	uint32_t dpll;
+	uint32_t dpll_md;
 	uint32_t fp0;
 	uint32_t fp1;
 };