ARM: dts: ls1021a: Enable the eTSEC ports on QDS and TWR

This enables the available eTSEC ethernet ports for the
ls1021aqds and ls1021atwr boards.
For the QDS, SGMII connections (via riser cards) are assumed
for the eTSEC0 and eTSEC1 ports as default configuration.

Signed-off-by: Alison Wang <alison.wang@freescale.com>
Signed-off-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>