arm64: dts: rockchip: Fix SDIO regulator supply properties on rk3399-firefly

A label reference without brackets is a path string, not a phandle as
intended. Add the missing brackets.

Fixes: a5002c41 ("arm64: dts: rockchip: add WiFi module support for Firefly-RK3399")
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220304202559.317749-1-robh@kernel.org


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