usb: gadget zero timer init fix

Initialize timer earlier so if an error occurs allocating USB request
or buffer request (zero_bind) Gadget Zero will not hang trying to
delete an uninitialized timer (zero_unbind).

Signed-off-by: David Lopo <lopo.david@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>