ARM: dts: exynos: Remove num-slots from exynos platforms

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 <jh80.chung@samsung.com>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/boot/dts/exynos5800-peach-pi.dts

@@ -667,7 +667,6 @@
 /* eMMC flash */
 &mmc_0 {
 	status = "okay";
-	num-slots = <1>;
 	mmc-hs200-1_8v;
 	mmc-hs400-1_8v;
 	cap-mmc-highspeed;
@@ -686,7 +685,6 @@
 /* WiFi SDIO module */
 &mmc_1 {
 	status = "okay";
-	num-slots = <1>;
 	non-removable;
 	cap-sdio-irq;
 	keep-power-in-suspend;
@@ -706,7 +704,6 @@
 /* uSD card */
 &mmc_2 {
 	status = "okay";
-	num-slots = <1>;
 	cap-sd-highspeed;
 	card-detect-delay = <200>;
 	clock-frequency = <400000000>;