misc/uss720: fix memory leak in uss720_probe
In the Linux kernel, the following vulnerability has been resolved:

misc/uss720: fix memory leak in uss720_probe

uss720_probe forgets to decrease the refcount of usbdev in uss720_probe.
Fix this by decreasing the refcount of usbdev by usb_put_dev.

BUG: memory leak
unreferenced object 0xffff888101113800 (size 2048):
  comm "kworker/0:1", pid 7, jiffies 4294956777 (age 28.870s)
  hex dump (first 32 bytes):
    ff ff ff ff 31 00 00 00 00 00 00 00 00 00 00 00  ....1...........
    00 00 00 00 00 00 00 00 00 00 00 00 03 00 00 00  ................
  backtrace:
    [<ffffffff82b8e822>] kmalloc include/linux/slab.h:554 [inline]
    [<ffffffff82b8e822>] kzalloc include/linux/slab.h:684 [inline]
    [<ffffffff82b8e822>] usb_alloc_dev+0x32/0x450 drivers/usb/core/usb.c:582
    [<ffffffff82b98441>] hub_port_connect drivers/usb/core/hub.c:5129 [inline]
    [<ffffffff82b98441>] hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
    [<ffffffff82b98441>] port_event drivers/usb/core/hub.c:5509 [inline]
    [<ffffffff82b98441>] hub_event+0x1171/0x20c0 drivers/usb/core/hub.c:5591
    [<ffffffff81259229>] process_one_work+0x2c9/0x600 kernel/workqueue.c:2275
    [<ffffffff81259b19>] worker_thread+0x59/0x5d0 kernel/workqueue.c:2421
    [<ffffffff81261228>] kthread+0x178/0x1b0 kernel/kthread.c:292
    [<ffffffff8100227f>] ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294