powerpc: dts: t1040rdb: add ports for Seville Ethernet switch

Define the network interface names for the switch ports and hook them up
to the 2 QSGMII PHYs that are onboard.

A conscious decision was taken to go along with the numbers that are
written on the front panel of the board and not with the hardware
numbers of the switch chip ports.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Maxim Kochetkov <fido_max@inbox.ru>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>