ARM: dts: lpc18xx: remove 'num-slots' property for dwmmc

Since 'num-slots' had already deprecated, remove the property in
device-tree file.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

arch/arm/boot/dts/lpc18xx.dtsi

@@ -115,7 +115,6 @@
 			compatible = "snps,dw-mshc";
 			reg = <0x40004000 0x1000>;
 			interrupts = <6>;
-			num-slots = <1>;
 			clocks = <&ccu2 CLK_SDIO>, <&ccu1 CLK_CPU_SDIO>;
 			clock-names = "ciu", "biu";
 			resets = <&rgu 20>;