Macro ioctl_ior_nr

macro_rules! ioctl_ior_nr {
    ($name:ident, $ty:expr, $nr:expr, $size:ty) => { ... };
    ($name:ident, $ty:expr, $nr:expr, $size:ty, $($v:ident),+) => { ... };
}

Declare an ioctl that reads data.