ocelot: Cancel delayed work before wq destruction

[ Upstream commit c5d139697d5d9ecf9c7cd92d7d7838a173508900 ]

Make sure the delayed work for stats update is not pending before
wq destruction.
This fixes the module unload path.
The issue is there since day 1.

Fixes: a556c76a ("net: mscc: Add initial Ocelot switch support")

Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>