ARM: dts: imx6q-cm-fx6: fix fec pinctrl

According to the schematics of CompuLab's sbc-fx6 baseboard and the
vendor devicetree GPIO_16 is *not* muxed to ENET_REF_CLK but to SPDIF_IN.

Remove the wrong pinctrl setting.

Fixes: 682d055e ("ARM: dts: Add initial support for cm-fx6.")
Signed-off-by: Christopher Spinrath <christopher.spinrath@rwth-aachen.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6q-cm-fx6.dts

@@ -183,7 +183,6 @@ MX6QDL_PAD_RGMII_TX_CTL__RGMII_TX_CTL	0x1b030
 			MX6QDL_PAD_ENET_REF_CLK__ENET_TX_CLK	0x1b0b0
 			MX6QDL_PAD_ENET_MDIO__ENET_MDIO		0x1b0b0
 			MX6QDL_PAD_ENET_MDC__ENET_MDC		0x1b0b0
-			MX6QDL_PAD_GPIO_16__ENET_REF_CLK	0x4001b0a8
 		>;
 	};