r8169: improve RTL8168b FIFO overflow workaround

r8169: improve RTL8168b FIFO overflow workaround

BugLink: https://bugs.launchpad.net/bugs/1900624
[ Upstream commit 6b02e407cbf8d421477ebb7792cd6380affcd313 ]

So far only the reset bit it set, but the handler executing the reset
is not scheduled. Therefore nothing will happen until some other action
schedules the handler. Improve this by ensuring that the handler is
scheduled.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Ian May <ian.may@canonical.com>