backlight: backlight: Fix doc for backlight_device_get_by_name

backlight_put() has been dropped, we should call put_device() to drop
the reference taken by backlight_device_get_by_name().

Fixes: 0f6a3256 ("backlight: backlight: Drop backlight_put()")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20221215071902.424005-1-linmq006@gmail.com

drivers/video/backlight/backlight.c

@@ -501,7 +501,7 @@ EXPORT_SYMBOL(backlight_device_get_by_type);
  *
  * This function looks up a backlight device by its name. It obtains a reference
  * on the backlight device and it is the caller's responsibility to drop the
- * reference by calling backlight_put().
+ * reference by calling put_device().
  *
  * Returns:
  * A pointer to the backlight device if found, otherwise NULL.