bus: ti-sysc: Detect i2c interconnect target module based on register layout

We can easily detect i2c based on it's non-standard module registers that
consist of two 32-bit registers accessed in 16-bit mode.

So far we don't have other 16-bit modules, so there's currently no need
to add a custom property for 16-bit register access.

Signed-off-by: Tony Lindgren <tony@atomide.com>