usb: gadget: f_hid: move list and spinlock inits from bind to alloc

In the Linux kernel, the following vulnerability has been resolved:

usb: gadget: f_hid: move list and spinlock inits from bind to alloc

There was an issue when you did the following:

- setup and bind an hid gadget

- open /dev/hidg0

- use the resulting fd in EPOLL_CTL_ADD

- unbind the UDC

- bind the UDC

- use the fd in EPOLL_CTL_DEL

When CONFIG_DEBUG_LIST was enabled, a list_del corruption was reported

within remove_wait_queue (via ep_remove_wait_queue). After some

debugging I found out that the queues, which f_hid registers via

poll_wait were the problem. These were initialized using

init_waitqueue_head inside hidg_bind. So effectively, the bind function

re-initialized the queues while there were still items in them.

The solution is to move the initialization from hidg_bind to hidg_alloc

to extend their lifetimes to the lifetime of the function instance.

Additionally, I found many other possibly problematic init calls in the

bind function, which I moved as well.