ARM: dts: socfpga: unuse the slot-node and deprecate the supports-highspeed for dw-mmc

dw-mmc controller can support multiple slots.
But, there are no use-cases anywhere. So we don't need to support the
slot-node for dw-mmc controller.
And "supports-highspeed" property in dw-mmc is deprecated.
"supports-highspeed" property can be replaced with "cap-sd/mmc-highspeed".

Signed-off-by: Jaehoon Chung <[e-mail]>
Reviewed-by: Tushar Behera <[e-mail]>
Reviewed-by: Ulf Hansson <[e-mail]>
Acked-by: Seungwon Jeon <[e-mail]>
Signed-off-by: Dinh Nguyen <[e-mail]>

arch/arm/boot/dts/socfpga_arria5.dtsi

···
 
 		dwmmc0@ff704000 {
 			num-slots = <1>;
-			supports-highspeed;
 			broken-cd;
-
-			slot@0 {
-				reg = <0>;
-				bus-width = <4>;
-			};
+			bus-width = <4>;
+			cap-mmc-highspeed;
+			cap-sd-highspeed;
 		};
 
 		sysmgr@ffd08000 {

arch/arm/boot/dts/socfpga_cyclone5.dtsi

···
 
 		dwmmc0@ff704000 {
 			num-slots = <1>;
-			supports-highspeed;
 			broken-cd;
-
-			slot@0 {
-				reg = <0>;
-				bus-width = <4>;
-			};
+			bus-width = <4>;
+			cap-mmc-highspeed;
+			cap-sd-highspeed;
 		};
 
 		ethernet@ff702000 {

arch/arm/boot/dts/socfpga_vt.dts

···
 
 		dwmmc0@ff704000 {
 			num-slots = <1>;
-			supports-highspeed;
 			broken-cd;
-
-			slot@0 {
-				reg = <0>;
-				bus-width = <4>;
-			};
+			bus-width = <4>;
+			cap-mmc-highspeed;
+			cap-sd-highspeed;
 		};
 
 		ethernet@ff700000 {