Revert "Optimized ARM RWSEM algorithm"

This reverts commit ea29ee37900b2634271a50445b46592b83195560.
Revert "Revert "ipv6: introdcue __ipv6_addr_needs_scope_id and ipv6_iface_scope_id helper functions""

This reverts commit 3590fce754b50bf950739c8fa79eb0e179525f00.