phy: lynx-28g: cancel the CDR check work item on the remove path

[ Upstream commit f200bab3 ]

The blamed commit added the CDR check work item but didn't cancel it on
the remove path. Fix this by adding a remove function which takes care
of it.

Fixes: 8f73b37c

 ("phy: add support for the Layerscape SerDes 28G")
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>