gpu: host1x: Fix a kernel-doc warning

Add @cache description to eliminate a kernel-doc warning.

include/linux/host1x.h:104: warning: Function parameter or member 'cache' not described in 'host1x_client'

Fixes: 1f39b1df ("drm/tegra: Implement buffer object cache")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Thierry Reding <treding@nvidia.com>
Cc: linux-tegra@vger.kernel.org
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Thierry Reding <treding@nvidia.com>

include/linux/host1x.h

@@ -81,6 +81,7 @@ struct host1x_client_ops {
  * @parent: pointer to parent structure
  * @usecount: reference count for this structure
  * @lock: mutex for mutually exclusive concurrency
+ * @cache: host1x buffer object cache
  */
 struct host1x_client {
 	struct list_head list;