media: v4l2-flash: Use led_classdev instead of led_classdev_flash for indicator

The V4L2 flash class initialisation expects struct led_classdev_flash that
describes an indicator but only uses struct led_classdev which is a field
iled_cdev in the struct. Use struct iled_cdev only.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>