Make the control active or inactive.
The control to (de)activate.
True if the control should become active.
This sets or clears the V4L2_CTRL_FLAG_INACTIVE flag atomically.
Does nothing if
ctrl == NULL.
This will usually be called from within the s_ctrl op.
The V4L2_EVENT_CTRL event will be generated afterwards.
This function assumes that the control handler is locked.