usb: gadget: zero: Convert timers to use timer_setup()

usb: gadget: zero: Convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly. Adds a static tracking variable to
match the timer global.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>