net: mscc: ocelot: install MAC addresses in .ndo_set_rx_mode from process context

Currently ocelot_set_rx_mode calls ocelot_mact_learn directly, which has
a very nice ocelot_mact_wait_for_completion at the end. Introduced in
commit 639c1b26 ("net: mscc: ocelot: Register poll timeout should be
wall time not attempts"), this function uses readx_poll_timeout which
triggers a lot of lockdep warnings and is also dangerous to use from
atomic context, potentially leading to lockups and panics.

Steen Hegelund added a poll timeout of 100 ms for checking the MAC
table, a duration which is clearly absurd to poll in atomic context.
So we need to defer the MAC table access to process context, which we do
via a dynamically allocated workqueue which contains all there is to
know about the MAC table operation it has to do.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20201212191612.222019-1-vladimir.oltean@nxp.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit ca0b272b)
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
[Xulin: Original patch taken from
https://github.com/vladimiroltean/linux/commits/felix-dsa-tag-vlan-stable

]
Signed-off-by: Xulin Sun <xulin.sun@windriver.com>