[patch] i915: fix impossible BUG_ON() test

[Dan Carpenter]

obj_priv->pin_count is unsigned so the BUG_ON(obj_priv->pin_count < 0)
will never trigger.

Signed-off-by: Dan Carpenter <error27 at gmail.com>

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 8eb8453..151d9c8 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4082,10 +4082,11 @@ i915_gem_object_unpin(struct drm_gem_object *obj)
 	struct drm_i915_gem_object *obj_priv = to_intel_bo(obj);
 
 	WARN_ON(i915_verify_lists(dev));
-	obj_priv->pin_count--;
-	BUG_ON(obj_priv->pin_count < 0);
+	BUG_ON(obj_priv->pin_count == 0);
 	BUG_ON(obj_priv->gtt_space == NULL);
 
+	obj_priv->pin_count--;
+
 	/* If the object is no longer pinned, and is
 	 * neither active nor being flushed, then stick it on
 	 * the inactive list