arm64: dts: rockchip: fix rk356x pcie msg interrupt name

The expected name by the binding at this position is "msg" and the SoC's
manual also calls the interrupt in question "msg", so fix the rk356x dtsi
to use the correct name.

Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20231114153834.934978-1-heiko@sntech.de