media: Add registration helpers for V4L2 flash sub-devices
This patch adds helper functions for registering/unregistering
LED Flash class devices as V4L2 sub-devices. The functions should
be called from the LED subsystem device driver. In case the
support for V4L2 Flash sub-devices is disabled in the kernel
config the functions' empty versions will be used.
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com> Acked-by: Kyungmin Park <kyungmin.park@samsung.com> Cc: Sakari Ailus <sakari.ailus@iki.fi> Cc: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Bryan Wu <cooloney@gmail.com>