MIPS: DTS: Remove num-slots from Pistachio SoC

dwmmc driver deprecated num-slots and plan to get rid of it finally.
Just move a step to cleanup it from DT.

Cc: Jaehoon Chung <[email protected]>
Signed-off-by: Shawn Lin <[email protected]>
Acked-by: James Hartley <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Jaehoon Chung <[email protected]>
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/16741/
Signed-off-by: James Hogan <[email protected]>

Author: shawn1221

arch/mips/boot/dts/img/pistachio.dtsi

@@ -805,7 +805,6 @@
 		pinctrl-0 = <&sdhost_pins>;
 		pinctrl-names = "default";
 		fifo-depth = <0x20>;
-		num-slots = <1>;
 		clock-frequency = <50000000>;
 		bus-width = <8>;
 		cap-mmc-highspeed;