drm/i915: fix WC mapping in non-GEM i915 code.

[airlied - taken from mailing list posting]

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 81f1cff..2d797ff 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -202,7 +202,7 @@
 		dev_priv->ring.map.flags = 0;
 		dev_priv->ring.map.mtrr = 0;
 
-		drm_core_ioremap(&dev_priv->ring.map, dev);
+		drm_core_ioremap_wc(&dev_priv->ring.map, dev);
 
 		if (dev_priv->ring.map.handle == NULL) {
 			i915_dma_cleanup(dev);