drm/i915: fix unused var

drivers/gpu/drm/i915/i915_dma.c: In function 'i915_driver_load':
drivers/gpu/drm/i915/i915_dma.c:1114: warning: 'll_base' may be used uninitialized in this function

Partly this is because gcc isn't smart enough.  But `ll_base' does get used
uninitialised in the DRM_DEBUG() call.

Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NEric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/i915_dma.c

@@ -1121,7 +1121,8 @@ static void i915_setup_compression(struct drm_device *dev, int size)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_mm_node *compressed_fb, *compressed_llb;
-	unsigned long cfb_base, ll_base;
+	unsigned long cfb_base;
+	unsigned long ll_base = 0;
 
 	/* Leave 1M for line length buffer & misc. */
 	compressed_fb = drm_mm_search_free(&dev_priv->vram, size, 4096, 0);