drm/i915: Don't call sg_free_table() if sg_alloc_table() fails

One needs to call __sg_free_table() if __sg_alloc_table() fails, but
sg_alloc_table() does that for us already.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewd-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -1774,7 +1774,6 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 
 	page_count = obj->base.size / PAGE_SIZE;
 	if (sg_alloc_table(st, page_count, GFP_KERNEL)) {
-		sg_free_table(st);
 		kfree(st);
 		return -ENOMEM;
 	}