drm/i915: Call the unlocked version of i915_gem_object_get_pages()

When we hold for the lock for swapping out the shmem pages for the
physically contiguous pages, we have to call the unlocked version of
get_pages!

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101934
Fixes: 35d23516946e ("drm/i915: Make i915_gem_object_phys_attach() use obj->mm.lock more appropriately")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20170726181602.23527-2-chris@chris-wilson.co.uk
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -5324,7 +5324,7 @@ int i915_gem_object_attach_phys(struct drm_i915_gem_object *obj, int align)
 	pages = obj->mm.pages;
 	obj->ops = &i915_gem_phys_ops;
 
-	err = __i915_gem_object_get_pages(obj);
+	err = ____i915_gem_object_get_pages(obj);
 	if (err)
 		goto err_xfer;