drm/i915: Read wm values from hardware at init on CHV

Read out the current watermark settings from the hardware at driver init
time. This will allow us to compare the newly calculated values against
the currrent ones and potentially avoid needless WM updates.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Clint Taylor <Clinton.A.Taylor@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 ea9caf2..2009ba5 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1515,6 +1515,8 @@
 		uint8_t sprite[2];
 		uint8_t primary;
 	} ddl[3];
+	uint8_t level;
+	bool cxsr;
 };
 
 struct skl_ddb_entry {