drm/vmwgfx/vmwgfx_cotable: Fix a couple of simple documentation problems

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/vmwgfx/vmwgfx_cotable.c:72: warning: Function parameter or member 'unbind_func' not described in 'vmw_cotable_info'
 drivers/gpu/drm/vmwgfx/vmwgfx_cotable.c:308: warning: Function parameter or member 'val_buf' not described in 'vmw_cotable_unbind'

Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Roland Scheidegger <sroland@vmware.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210115181601.3432599-3-lee.jones@linaro.org

drivers/gpu/drm/vmwgfx/vmwgfx_cotable.c

@@ -63,6 +63,7 @@ struct vmw_cotable {
  * @min_initial_entries: Min number of initial intries at cotable allocation
  * for this cotable type.
  * @size: Size of each entry.
+ * @unbind_func: Unbind call-back function.
  */
 struct vmw_cotable_info {
 	u32 min_initial_entries;
@@ -297,7 +298,7 @@ int vmw_cotable_scrub(struct vmw_resource *res, bool readback)
  *
  * @res: Pointer to the cotable resource.
  * @readback: Whether to read back cotable data to the backup buffer.
- * val_buf: Pointer to a struct ttm_validate_buffer prepared by the caller
+ * @val_buf: Pointer to a struct ttm_validate_buffer prepared by the caller
  * for convenience / fencing.
  *
  * Unbinds the cotable from the device and fences the backup buffer.