arm64: dts: rockchip: rename sdhci nodename to mmc on rk3399

arm64: dts: rockchip: rename sdhci nodename to mmc on rk3399

A test with the command below gives for example this error:

/arch/arm64/boot/dts/rockchip/rk3399-evb.dt.yaml:
sdhci@fe330000: $nodename:0: 'sdhci@fe330000'
does not match '^mmc(@.*)?$'

Fix it by renaming sdhci to mmc.

make ARCH=arm64 dtbs_check
DT_SCHEMA_FILES=Documentation/devicetree/bindings/
mmc/arasan,sdhci.yaml

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20201116132311.8318-1-jbx6244@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>