ARM: dts: Configure interconnect target module for am3 sham

We can now probe devices with device tree only configuration using
ti-sysc interconnect target module driver. Let's configure the
module, but keep the legacy "ti,hwmods" peroperty to avoid new boot
time warnings. The legacy property will be removed in later patches
together with the legacy platform data.

I could not find any documentation for the sysc register on this one,
but it seems to work just fine with "ti,sysc-omap3-sham" compatible
style configuration.

Cc: Keerthy <j-keerthy@ti.com>
Cc: Tero Kristo <t-kristo@ti.com>
Tested-by: Tero Kristo <t-kristo@ti.com>
Reviewed-by: Tero Kristo <t-kristo@ti.com>
Tested-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>