Split the code to find and add iicbus children out to its own function.
Move the decision to take an early exit from that function after adding
children based on FDT data into the #ifdef FDT block, so that it doesn't
offend coverity's notion of how the code should be written. (What's the
point of compilers optimizing away dead code if static analyzers won't
let you use the feature in conjuction with an #ifdef block?)

Reported by: coverity via vangyzen@