usbip: tools: Fix detach_port() invalid port error path

The detach_port() doesn't return error
when detach is attempted on an invalid port.

Fixes: 40ecdeb1 ("usbip: usbip_detach: fix to check for invalid ports")
Cc: stable@vger.kernel.org
Reviewed-by: Hongren Zheng <i@zenithal.me>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Zongmin Zhou <zhouzongmin@kylinos.cn>
Link: https://lore.kernel.org/r/20241024022700.1236660-1-min_halo@163.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>