ARM: dts: mxs: add the "clock-names" for gpmi-nand

The current DT nodes for mx23/mx28 miss the `clocks-names` item for gpmi-nand.
So the gpmi-nand driver could not find the proper clock.

This patch fixes this issue.
Signed-off-by: Huang Shijie <b32955@freescale.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/boot/dts/imx23.dtsi

@@ -69,6 +69,7 @@ gpmi-nand@8000c000 {
 				interrupts = <13>, <56>;
 				interrupt-names = "gpmi-dma", "bch";
 				clocks = <&clks 34>;
+				clock-names = "gpmi_io";
 				fsl,gpmi-dma-channel = <4>;
 				status = "disabled";
 			};

arch/arm/boot/dts/imx28.dtsi

@@ -85,6 +85,7 @@ gpmi-nand@8000c000 {
 				interrupts = <88>, <41>;
 				interrupt-names = "gpmi-dma", "bch";
 				clocks = <&clks 50>;
+				clock-names = "gpmi_io";
 				fsl,gpmi-dma-channel = <4>;
 				status = "disabled";
 			};