net, neigh: Set lower cap for neigh_managed_work rearming

net, neigh: Set lower cap for neigh_managed_work rearming

Yuwei reported that plain reuse of DELAY_PROBE_TIME to rearm work queue
in neigh_managed_work is problematic if user explicitly configures the
DELAY_PROBE_TIME to 0 for a neighbor table. Such misconfig can then hog
CPU to 100% processing the system work queue. Instead, set lower interval
bound to HZ which is totally sufficient. Yuwei is additionally looking
into making the interval separately configurable from DELAY_PROBE_TIME.

Reported-by: Yuwei Wang <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Link: https://lore.kernel.org/netdev/[email protected]
Reviewed-by: Nikolay Aleksandrov <[email protected]>
Link: https://lore.kernel.org/r/3b8c5aa906c52c3a8c995d1b2e8ccf650ea7c716.1653432794.git.daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <[email protected]>