bus: ti-sysc: Manage clocks for the interconnect target module in all cases

We are currently not managing interconnect target module clocks in the
for legacy platform data based case. This causes a problem for using the
platform data based functions when dropping the platform data for the
interconnect target module configuration.

To avoid a situation where we need to populate the main and optional
clocks also for the platform data based functions, let's just manage the
clocks directly in ti-sysc driver. This means that until the interconnect
target module confugration platform data is dropped our use count for
clk_enable() will be 2 instead of 1.

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