usb: wusbcore: remove unreachable code

The call to wusb_dev_sysfs_rm() which is just after return will never
be executed. On checking the code, wusb_dev_sysfs_add() is the last one
to be executed so even if that fails we do not need wusb_dev_sysfs_rm()
in the error path.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>