ARM: orion5x: update I2C description at SoC level

This commit fixes the Orion5x SoC definition to:

 * Not define a clock-frequency, as it should be described on a
   per-board basis.

 * Declare the appropriate clock reference, so that the driver can do
   correct divisors calculations for the I2C bus.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1398202002-28530-26-git-send-email-thomas.petazzoni@free-electrons.com
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/orion5x.dtsi

@@ -56,7 +56,7 @@
 				#address-cells = <1>;
 				#size-cells = <0>;
 				interrupts = <5>;
-				clock-frequency = <100000>;
+				clocks = <&core_clk 0>;
 				status = "disabled";
 			};