net: dsa: felix: use kmemdup() to replace kmalloc + memcpy

Fix following coccicheck warning:
/drivers/net/dsa/ocelot/felix_vsc9959.c:1627:13-20:
WARNING opportunity for kmemdup
/drivers/net/dsa/ocelot/felix_vsc9959.c:1506:16-23:
WARNING opportunity for kmemdup

Signed-off-by: Yihao Han <hanyihao@vivo.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20211207064419.38632-1-hanyihao@vivo.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>