When constructing a ControlValue from an enum value, an explicit cast to
int32_t is needed as we use int32_t as the underlying type for all
enumerated controls. This makes users of ControlValue more complex. To
simplify them, specialize the control_type template for enum types, to
support construction of ControlValue directly without a cast.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>