arm64: dts: rockchip: 'Fix' nanopi4 uSD card detect

For whatever reason, the sdmmc_dectn function isn't working properly
as-is, and microSD insertion and removal goes unnoticed. Using the pin
as a GPIO interrupt instead is rather noisy without any debouncing, but
is good enough to make it useful until someone feels inclined to figure
out how the vendor kernel/firmware gets the dedicated function to work
with no obvious difference in the pinmux/GRF configuration. Let's also
take the opportunity to tweak the node name so that all related pins
end up grouped together in the compiled DTB.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>