drm/i915: Remove use on gma_bus_addr on gen6+

We have enough info to not use the intel_gtt bridge stuff.

v2: Move setup of mappable_base above the legacy init stuff because we
still need that on older platforms. (Daniel)

v3: Remove the dev_priv hunk which was rebased in by accident

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com> (v2)
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index bb62213..468d2a0 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1426,7 +1426,7 @@
 	if (!ap)
 		return;
 
-	ap->ranges[0].base = dev_priv->mm.gtt->gma_bus_addr;
+	ap->ranges[0].base = dev_priv->gtt.mappable_base;
 	ap->ranges[0].size =
 		dev_priv->mm.gtt->gtt_mappable_entries << PAGE_SHIFT;
 	primary =
@@ -1543,7 +1543,6 @@
 	}
 
 	aperture_size = dev_priv->mm.gtt->gtt_mappable_entries << PAGE_SHIFT;
-	dev_priv->gtt.mappable_base = dev_priv->mm.gtt->gma_bus_addr;
 
 	dev_priv->gtt.mappable =
 		io_mapping_create_wc(dev_priv->gtt.mappable_base,