powerpc: t1040qds: Use generic ethsw commands

The commands for the VSC9953 l2 switch from T1040 became generic in
patch https://patchwork.ozlabs.org/patch/499748/

 and the define
was renamed.

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@nxp.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: York Sun <york.sun@nxp.com>