usbip: tools: add usage of device mode in usbip_list.c

The option '-d/--device' was implemented in 'usbip list' but not
shown in usage. Hence this commit adds this option to usage.

Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Hongren Zheng <i@zenithal.me>
Link: https://lore.kernel.org/r/YFrwq75Uyef3c9gz@Sun


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