docs: dts: Add documentation for hi6220 SoC ION node

Documentation for hi6220 SoC ION node

Signed-off-by: Chen Feng <puck.chen@hisilicon.com>
Signed-off-by: Yu Dongbin <yudongbin@hisilicon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 file changed