driver: uio: fix possible memory leak in __uio_register_device

mainline inclusion
from mainline-5.x
commit: 1a392b3d
category: bugfix
bugzilla: NA
CVE: NA

---------------------------

'idev' is malloced in __uio_register_device() and leak free it before
leaving from the uio_get_minor() error handing case, it will cause
memory leak.

Fixes: a93e7b33 ("uio: Prevent device destruction while fds are open")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Reviewed-by: Hamish Martin <hamish.martin@alliedtelesis.co.nz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>