arm64: dts: rockchip: Document unused device on i2c1

arm64: dts: rockchip: Document unused device on i2c1

Update the i2c1 bus noting that the unknown/unused device at 0x3c is an
iSmartWare SW2001 "encryption IC".

Based on the documentation I was able to find, this IC appears to be
used to authenticate a device for certain programs to ensure they only
run on authorized devices as a form of digital rights management.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Link: https://lore.kernel.org/r/20250604024119.381337-1-macroalpha82@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>