arm64: dts: remove no-emmc from mmc node for Rockchip PX5 EVB

A test with the command below does not detect all errors
in combination with 'additionalProperties: false' and
allOf:
  - $ref: "synopsys-dw-mshc-common.yaml#"
allOf:
  - $ref: "mmc-controller.yaml#"

'additionalProperties' applies to all properties that are not
accounted-for by 'properties' or 'patternProperties' in
the immediate schema.

First when we combine rockchip-dw-mshc.yaml,
synopsys-dw-mshc-common.yaml and mmc-controller.yaml it gives
this error:

arch/arm64/boot/dts/rockchip/rk3368-px5-evb.dt.yaml: mmc@ff0c0000:
'no-emmc' does not match any of the regexes:
'^.*@[0-9]+$', '^clk-phase-(legacy|sd-hs|mmc-(hs|hs[24]00|ddr52)|
uhs-(sdr(12|25|50|104)|ddr50))$', 'pinctrl-[0-9]+'

'no-emmc' is not a valid property name for mmc nodes,
so remove it.

make ARCH=arm64 dtbs_check
DT_SCHEMA_FILES=Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.yaml
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20200307134841.13803-3-jbx6244@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3368-px5-evb.dts

@@ -239,7 +239,6 @@ &sdmmc {
 	cap-mmc-highspeed;
 	cap-sd-highspeed;
 	card-detect-delay = <200>;
-	no-emmc;
 	no-sdio;
 	sd-uhs-sdr12;
 	sd-uhs-sdr25;