Changed usbip_network, usbip_attach, usbip_list, and usbipd to use
and propagate the new error codes in server reply messages.

usbip_net_recv_op_common() is changed to take a pointer to status
return the status returned in the op_common.status to callers.

usbip_attach and usbip_list use the common interface to print error
messages to indicate why the request failed.

With this change the messages say why a request failed:

- when a client requests a device that is already exported:

usbip attach -r server_name -b 3-10.2
usbip: error: Attach Request for 3-10.2 failed - Device busy (exported)

- when a client requests a device that isn't exportable,

usbip attach -r server_name -b 3-10.4
usbip: error: Attach Request for 3-10.4 failed - Device not found
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>