Cast RawOpcode to the internal ioctl_code type (c_uint)

[jonlamb-gh]

The rustix RawOpcode type can vary depending on the target.
For example, targets that use the libc Linux configuration in rustix, the RawOpcode type is a type alias to c_ulong rather than c_uint.
I believe the UsbFsIoctl struct should remain the same in these configurations.

Discovered this while attempting to build for s390x-unknown-linux-gnu.

error[E0308]: mismatched types
  --> /root/.cargo/registry/src/index.crates.io-6f17d22bba15001f/nusb-0.1.6/src/platform/linux_usbfs/usbfs.rs:78:25
   |
78 |             ioctl_code: ioctl::NoneOpcode::<b'U', 23, ()>::OPCODE.raw(), // IOCTL_USBFS_CONNECT
   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `u32`, found `u64`

[kevinmehall]

Thanks!

[kevinmehall]

I don't think it actually matters, but the ioctl_code is a signed int in the kernel headers.