ARM: dts: imx: fix clocks for cspi

The CSPI controller has only one clock, but the driver spi-imx.c needs
clock "per" to calculate bitrate divisor.

Signed-off-by: Jonas Andersson <jonas@microbit.se>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/boot/dts/imx51.dtsi

@@ -631,7 +631,7 @@
 				compatible = "fsl,imx51-cspi", "fsl,imx35-cspi";
 				reg = <0x83fc0000 0x4000>;
 				interrupts = <38>;
-				clocks = <&clks 55>, <&clks 0>;
+				clocks = <&clks 55>, <&clks 55>;
 				clock-names = "ipg", "per";
 				status = "disabled";
 			};