ARM: imx6qp: adapt DT to changed FEC interrupts

On i.MX6QP the FEC interrupts are wired to the GPC, just like all other
device interrupts. This allows to FEC to wake the CPU from WFI, but for
this to work the kernel needs to know about the new IRQ routing.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>