net: lan966x: Fix usage of lan966x->mac_lock inside lan966x_mac_irq_handler

[ Upstream commit c1924684 ]

The problem with this spin lock is that it was just protecting the list
of the MAC entries in SW and not also the access to the MAC entries in HW.
Because the access to HW is indirect, then it could happen to have race
conditions.
For example when SW introduced an entry in MAC table and the irq mac is
trying to read something from the MAC.
Update such that also the access to MAC entries in HW is protected by
this lock.

Fixes: 5ccd66e0

 ("net: lan966x: add support for interrupts from analyzer")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>