arm64: dts: rockchip: fix pinctrl sleep nodename for rk3399.dtsi

A test with the command below aimed at powerpc generates
notifications in the Rockchip arm64 tree.

Fix pinctrl "sleep" nodename by renaming it to "suspend"
for rk3399.dtsi

make ARCH=arm64 dtbs_check
DT_SCHEMA_FILES=Documentation/devicetree/bindings/powerpc/sleep.yaml

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20210126110221.10815-2-jbx6244@gmail.com


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