ARM: dts: imx27-phytec-phycore: Add reset GPIO for FEC

FEC (KSZ8001L) reset pin is connected to GPIOC30.
Add this definition to dts.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>