uio: Fix stale info pointer in failed registration path

In the Linux kernel, the following vulnerability has been resolved:

uio: Fix stale info pointer in failed registration path

After device_add(), the UIO device is visible to userspace and /dev/uioX
can be opened. If a later setup step fails, __uio_register_device()
unwinds the device but leaves idev->info pointing at the caller-owned
struct uio_info.

That is unsafe when an opener races with the failed registration path.
The open file keeps a reference to the uio_device, while the caller sees
registration failure and may free its struct uio_info. Later file
operations can then follow idev->info and dereference freed memory.

Handle post-device_add() failures like unregister: remove UIO attributes
while the info pointer is still valid, then clear idev->info under
info_lock and wake existing waiters/async users before removing the
device and minor. This makes already-open file descriptors observe the
same "device gone" state as normal uio_unregister_device().