drm/udl: Don't re-initialize stuff at retrying the URB list allocation

udl_alloc_urb_list() retires the allocation if there is no enough room
left, and it reinitializes the stuff unnecessarily such as the linked
list head and the waitqueue, which could be harmful.  Those should be
outside the retry loop.

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220908095115.23396-12-tiwai@suse.de