rust: usb: fix broken call to T::disconnect()

A refactoring of Device::drvdata_obtain() broke T::disconnect() in the
USB abstractions.

"""
error[E0599]: no method named `data` found for struct `core::pin::Pin<kbox::Box<T, Kmalloc>>` in the current scope
  --> rust/kernel/usb.rs:92:34
   |
92 |         T::disconnect(intf, data.data());
   |                                  ^^^^ method not found in `core::pin::Pin<kbox::Box<T, Kmalloc>>`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0599`.
make[2]: *** [rust/Makefile:553: rust/kernel.o] Error 1
make[1]: *** [/builddir/build/BUILD/kernel-6.18.0-build/kernel-next-20251103/linux-6.18.0-0.0.next.20251103.436.vanilla.fc44.x86_64/Makefile:1316: prepare] Error 2
make: *** [Makefile:256: __sub-make] Error 2
"""

This slipped through, since the USB abstractions are globally disabled.
However, the USB tree recently enabled them, hence it showed up in
linux-next.

Reported-by: Thorsten Leemhuis <linux@leemhuis.info>
Closes: https://lore.kernel.org/all/1c8afbc0-e888-4702-9e4e-fa8aef0f97ae@leemhuis.info/
Fixes: 6bbaa93912 ("rust: device: narrow the generic of drvdata_obtain()")
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Thorsten Leemhuis <linux@leemhuis.info>
Link: https://patch.msgid.link/20251103110115.1925072-1-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

rust/kernel/usb.rs

@@ -89,7 +89,7 @@ impl<T: Driver + 'static> Adapter<T> {
         // and stored a `Pin<KBox<T>>`.
         let data = unsafe { dev.drvdata_obtain::<T>() };
 
-        T::disconnect(intf, data.data());
+        T::disconnect(intf, data.as_ref());
     }
 }