Revert "net: rtnetlink: remove local list in __linkwatch_run_queue()"

Revert "net: rtnetlink: remove local list in __linkwatch_run_queue()"

This reverts commit b8dbbbc535a9 ("net: rtnetlink: remove local list
in __linkwatch_run_queue()"). It's evidently broken when there's a
non-urgent work that gets added back, and then the loop can never
finish.

While reverting, add a note about that.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: b8dbbbc535a9 ("net: rtnetlink: remove local list in __linkwatch_run_queue()")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>