arm64: dts: rockchip: enable NanoPC-T6 MiniPCIe power

The NanoPC-T6 has a Mini PCIe slot intended to be used for a 4G or LTE
modem. This slot has no PCIe functionality, only USB 2.0 pins are wired
to the SoC, and USIM pins are wired to a SIM card slot on the board.
Define the 3.3v supply for the slot so it can be used.

Signed-off-by: Hugh Cole-Baker <sigmaris@gmail.com>
Link: https://lore.kernel.org/r/20240109202729.54292-1-sigmaris@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>