ARM: dts: imx6qdl: use interrupts-extended for fec

We need to be able to override interrupts in board file to
workaround a hardware bug for ethernet interrupts
waking the processor by using interrupts-extended.
So, use interrupts-extended here as well.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>