UPSTREAM: arm64: dts: rockchip: assign a fixed index to mmc devices on px30 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: I3a61c02162e975b1ba4f8635b36965f99f0b60d7
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20210118155242.7172-3-jbx6244@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Wenping Zhang <wenping.zhang@rock-chips.com>
Signed-off-by: Tao Huang <huangtao@rock-chips.com>
(cherry picked from commit 84b2c2c872)

arch/arm64/boot/dts/rockchip/px30.dtsi

@@ -30,6 +30,9 @@
 		i2c1 = &i2c1;
 		i2c2 = &i2c2;
 		i2c3 = &i2c3;
+		mmc0 = &sdmmc;
+		mmc1 = &sdio;
+		mmc2 = &emmc;
 		serial0 = &uart0;
 		serial1 = &uart1;
 		serial2 = &uart2;