Function ral::return_register

pub fn return_register<ValueType, RegisterType>(
    holder: &AtomicPtr<VolatileCell<ValueType>>, 
    register: &mut R<ValueType, RegisterType>
) where
    ValueType: Copy + Not<Output = ValueType> + BitAnd<Output = ValueType> + BitOr<Output = ValueType>,
    RegisterType: Register<RegisterType = RegisterType, ValueType = ValueType>, 

Releases register, so it can be borrowed again