UPSTREAM: arm64: dts: rockchip: assign a fixed index to mmc devices on rk3368 boards

Recently introduced async probe on mmc devices can shuffle block IDs.
Pin them to fixed values to ease booting in environments where UUIDs are
not practical. Use newly introduced aliases for mmcblk devices from [1].
The sort order is based on reg address.

[1] https://patchwork.kernel.org/patch/11747669/

Change-Id: I9ae6f07f295553990118596f379275876d852497
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20210118155242.7172-5-jbx6244@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Wenping Zhang <wenping.zhang@rock-chips.com>
(cherry picked from commit 0523b124aa)

arch/arm64/boot/dts/rockchip/rk3368.dtsi

@@ -33,6 +33,9 @@
 		i2c3 = &i2c3;
 		i2c4 = &i2c4;
 		i2c5 = &i2c5;
+		mmc0 = &sdmmc;
+		mmc1 = &sdio0;
+		mmc2 = &emmc;
 		serial0 = &uart0;
 		serial1 = &uart1;
 		serial2 = &uart2;