arm64: dts: rockchip: Add sdio node to rock-5b

Enable SDIO on Radxa ROCK 5 Model B M.2 Key E. Add sdio node and alias as mmc2.
Add regulator for the 3.3 V rail bringing it up during boot. Make sure EKEY_EN
is muxed as GPIO.

Signed-off-by: Tamás Szűcs <tszucs@protonmail.ch>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20230924203740.65744-1-tszucs@protonmail.ch
Signed-off-by: Heiko Stuebner <heiko@sntech.de>