ACPI: video - remove unsafe uses of list_for_each_safe()

list_for_each_safe() only protects list from list alterations
performed by the same thread. One still needs to implement
proper locking when list is being accessed from several threads.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>