ARM: dts: imx6: fix fec ptp clock slow 10 time

ptp should use enet_ref instead of pll6_enet
pll6_enet is fixed 500Mhz.
There are divider between enet_ref and pll6_enet
Signed-off-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx6q.dtsi

@@ -866,7 +866,7 @@ fec: ethernet@02188000 {
 				compatible = "fsl,imx6q-fec";
 				reg = <0x02188000 0x4000>;
 				interrupts = <0 118 0x04 0 119 0x04>;
-				clocks = <&clks 117>, <&clks 117>, <&clks 177>;
+				clocks = <&clks 117>, <&clks 117>, <&clks 190>;
 				clock-names = "ipg", "ahb", "ptp";
 				status = "disabled";
 			};